sqlglot.executor.python API documentation

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# sqlglot.executor.python

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      1import ast
      2import collections
      3import itertools
      4import math
      5
      6from sqlglot import exp, generator, planner, tokens
      7from sqlglot.dialects.dialect import Dialect, inline_array_sql
      8from sqlglot.errors import ExecuteError
      9from sqlglot.executor.context import Context
     10from sqlglot.executor.env import ENV
     11from sqlglot.executor.table import RowReader, Table
     12from sqlglot.helper import csv_reader, subclasses
     13
     14
     15class PythonExecutor:
     16    def __init__(self, env=None, tables=None):
     17        self.generator = Python().generator(identify=True, comments=False)
     18        self.env = {**ENV, **(env or {})}
     19        self.tables = tables or {}
     20
     21    def execute(self, plan):
     22        running = set()
     23        finished = set()
     24        queue = set(plan.leaves)
     25        contexts = {}
     26
     27        while queue:
     28            node = queue.pop()
     29            try:
     30                context = self.context(
     31                    {
     32                        name: table
     33                        for dep in node.dependencies
     34                        for name, table in contexts[dep].tables.items()
     35                    }
     36                )
     37                running.add(node)
     38
     39                if isinstance(node, planner.Scan):
     40                    contexts[node] = self.scan(node, context)
     41                elif isinstance(node, planner.Aggregate):
     42                    contexts[node] = self.aggregate(node, context)
     43                elif isinstance(node, planner.Join):
     44                    contexts[node] = self.join(node, context)
     45                elif isinstance(node, planner.Sort):
     46                    contexts[node] = self.sort(node, context)
     47                elif isinstance(node, planner.SetOperation):
     48                    contexts[node] = self.set_operation(node, context)
     49                else:
     50                    raise NotImplementedError
     51
     52                running.remove(node)
     53                finished.add(node)
     54
     55                for dep in node.dependents:
     56                    if dep not in running and all(d in contexts for d in dep.dependencies):
     57                        queue.add(dep)
     58
     59                for dep in node.dependencies:
     60                    if all(d in finished for d in dep.dependents):
     61                        contexts.pop(dep)
     62            except Exception as e:
     63                raise ExecuteError(f"Step '{node.id}' failed: {e}") from e
     64
     65        root = plan.root
     66        return contexts[root].tables[root.name]
     67
     68    def generate(self, expression):
     69        """Convert a SQL expression into literal Python code and compile it into bytecode."""
     70        if not expression:
     71            return None
     72
     73        sql = self.generator.generate(expression)
     74        return compile(sql, sql, "eval", optimize=2)
     75
     76    def generate_tuple(self, expressions):
     77        """Convert an array of SQL expressions into tuple of Python byte code."""
     78        if not expressions:
     79            return tuple()
     80        return tuple(self.generate(expression) for expression in expressions)
     81
     82    def context(self, tables):
     83        return Context(tables, env=self.env)
     84
     85    def table(self, expressions):
     86        return Table(
     87            expression.alias_or_name if isinstance(expression, exp.Expression) else expression
     88            for expression in expressions
     89        )
     90
     91    def scan(self, step, context):
     92        source = step.source
     93
     94        if source and isinstance(source, exp.Expression):
     95            source = source.name or source.alias
     96
     97        condition = self.generate(step.condition)
     98        projections = self.generate_tuple(step.projections)
     99
    100        if source is None:
    101            context, table_iter = self.static()
    102        elif source in context:
    103            if not projections and not condition:
    104                return self.context({step.name: context.tables[source]})
    105            table_iter = context.table_iter(source)
    106        elif isinstance(step.source, exp.Table) and isinstance(step.source.this, exp.ReadCSV):
    107            table_iter = self.scan_csv(step)
    108            context = next(table_iter)
    109        else:
    110            context, table_iter = self.scan_table(step)
    111
    112        if projections:
    113            sink = self.table(step.projections)
    114        else:
    115            sink = self.table(context.columns)
    116
    117        for reader in table_iter:
    118            if len(sink) >= step.limit:
    119                break
    120
    121            if condition and not context.eval(condition):
    122                continue
    123
    124            if projections:
    125                sink.append(context.eval_tuple(projections))
    126            else:
    127                sink.append(reader.row)
    128
    129        return self.context({step.name: sink})
    130
    131    def static(self):
    132        return self.context({}), [RowReader(())]
    133
    134    def scan_table(self, step):
    135        table = self.tables.find(step.source)
    136        context = self.context({step.source.alias_or_name: table})
    137        return context, iter(table)
    138
    139    def scan_csv(self, step):
    140        alias = step.source.alias
    141        source = step.source.this
    142
    143        with csv_reader(source) as reader:
    144            columns = next(reader)
    145            table = Table(columns)
    146            context = self.context({alias: table})
    147            yield context
    148            types = []
    149
    150            for row in reader:
    151                if not types:
    152                    for v in row:
    153                        try:
    154                            types.append(type(ast.literal_eval(v)))
    155                        except (ValueError, SyntaxError):
    156                            types.append(str)
    157                context.set_row(tuple(t(v) for t, v in zip(types, row)))
    158                yield context.table.reader
    159
    160    def join(self, step, context):
    161        source = step.name
    162
    163        source_table = context.tables[source]
    164        source_context = self.context({source: source_table})
    165        column_ranges = {source: range(0, len(source_table.columns))}
    166
    167        for name, join in step.joins.items():
    168            table = context.tables[name]
    169            start = max(r.stop for r in column_ranges.values())
    170            column_ranges[name] = range(start, len(table.columns) + start)
    171            join_context = self.context({name: table})
    172
    173            if join.get("source_key"):
    174                table = self.hash_join(join, source_context, join_context)
    175            else:
    176                table = self.nested_loop_join(join, source_context, join_context)
    177
    178            source_context = self.context(
    179                {
    180                    name: Table(table.columns, table.rows, column_range)
    181                    for name, column_range in column_ranges.items()
    182                }
    183            )
    184            condition = self.generate(join["condition"])
    185            if condition:
    186                source_context.filter(condition)
    187
    188        condition = self.generate(step.condition)
    189        projections = self.generate_tuple(step.projections)
    190
    191        if not condition and not projections:
    192            return source_context
    193
    194        sink = self.table(step.projections if projections else source_context.columns)
    195
    196        for reader, ctx in source_context:
    197            if condition and not ctx.eval(condition):
    198                continue
    199
    200            if projections:
    201                sink.append(ctx.eval_tuple(projections))
    202            else:
    203                sink.append(reader.row)
    204
    205            if len(sink) >= step.limit:
    206                break
    207
    208        if projections:
    209            return self.context({step.name: sink})
    210        else:
    211            return self.context(
    212                {
    213                    name: Table(table.columns, sink.rows, table.column_range)
    214                    for name, table in source_context.tables.items()
    215                }
    216            )
    217
    218    def nested_loop_join(self, _join, source_context, join_context):
    219        table = Table(source_context.columns + join_context.columns)
    220
    221        for reader_a, _ in source_context:
    222            for reader_b, _ in join_context:
    223                table.append(reader_a.row + reader_b.row)
    224
    225        return table
    226
    227    def hash_join(self, join, source_context, join_context):
    228        source_key = self.generate_tuple(join["source_key"])
    229        join_key = self.generate_tuple(join["join_key"])
    230        left = join.get("side") == "LEFT"
    231        right = join.get("side") == "RIGHT"
    232
    233        results = collections.defaultdict(lambda: ([], []))
    234
    235        for reader, ctx in source_context:
    236            results[ctx.eval_tuple(source_key)][0].append(reader.row)
    237        for reader, ctx in join_context:
    238            results[ctx.eval_tuple(join_key)][1].append(reader.row)
    239
    240        table = Table(source_context.columns + join_context.columns)
    241        nulls = [(None,) * len(join_context.columns if left else source_context.columns)]
    242
    243        for a_group, b_group in results.values():
    244            if left:
    245                b_group = b_group or nulls
    246            elif right:
    247                a_group = a_group or nulls
    248
    249            for a_row, b_row in itertools.product(a_group, b_group):
    250                table.append(a_row + b_row)
    251
    252        return table
    253
    254    def aggregate(self, step, context):
    255        group_by = self.generate_tuple(step.group.values())
    256        aggregations = self.generate_tuple(step.aggregations)
    257        operands = self.generate_tuple(step.operands)
    258
    259        if operands:
    260            operand_table = Table(self.table(step.operands).columns)
    261
    262            for reader, ctx in context:
    263                operand_table.append(ctx.eval_tuple(operands))
    264
    265            for i, (a, b) in enumerate(zip(context.table.rows, operand_table.rows)):
    266                context.table.rows[i] = a + b
    267
    268            width = len(context.columns)
    269            context.add_columns(*operand_table.columns)
    270
    271            operand_table = Table(
    272                context.columns,
    273                context.table.rows,
    274                range(width, width + len(operand_table.columns)),
    275            )
    276
    277            context = self.context(
    278                {
    279                    None: operand_table,
    280                    **context.tables,
    281                }
    282            )
    283
    284        context.sort(group_by)
    285
    286        group = None
    287        start = 0
    288        end = 1
    289        length = len(context.table)
    290        table = self.table(list(step.group) + step.aggregations)
    291        condition = self.generate(step.condition)
    292
    293        def add_row():
    294            if not condition or context.eval(condition):
    295                table.append(group + context.eval_tuple(aggregations))
    296
    297        if length:
    298            for i in range(length):
    299                context.set_index(i)
    300                key = context.eval_tuple(group_by)
    301                group = key if group is None else group
    302                end += 1
    303                if key != group:
    304                    context.set_range(start, end - 2)
    305                    add_row()
    306                    group = key
    307                    start = end - 2
    308                if len(table.rows) >= step.limit:
    309                    break
    310                if i == length - 1:
    311                    context.set_range(start, end - 1)
    312                    add_row()
    313        elif step.limit > 0 and not group_by:
    314            context.set_range(0, 0)
    315            table.append(context.eval_tuple(aggregations))
    316
    317        context = self.context({step.name: table, **{name: table for name in context.tables}})
    318
    319        if step.projections:
    320            return self.scan(step, context)
    321        return context
    322
    323    def sort(self, step, context):
    324        projections = self.generate_tuple(step.projections)
    325        projection_columns = [p.alias_or_name for p in step.projections]
    326        all_columns = list(context.columns) + projection_columns
    327        sink = self.table(all_columns)
    328        for reader, ctx in context:
    329            sink.append(reader.row + ctx.eval_tuple(projections))
    330
    331        sort_ctx = self.context(
    332            {
    333                None: sink,
    334                **{table: sink for table in context.tables},
    335            }
    336        )
    337        sort_ctx.sort(self.generate_tuple(step.key))
    338
    339        if not math.isinf(step.limit):
    340            sort_ctx.table.rows = sort_ctx.table.rows[0 : step.limit]
    341
    342        output = Table(
    343            projection_columns,
    344            rows=[r[len(context.columns) : len(all_columns)] for r in sort_ctx.table.rows],
    345        )
    346        return self.context({step.name: output})
    347
    348    def set_operation(self, step, context):
    349        left = context.tables[step.left]
    350        right = context.tables[step.right]
    351
    352        sink = self.table(left.columns)
    353
    354        if issubclass(step.op, exp.Intersect):
    355            sink.rows = list(set(left.rows).intersection(set(right.rows)))
    356        elif issubclass(step.op, exp.Except):
    357            sink.rows = list(set(left.rows).difference(set(right.rows)))
    358        elif issubclass(step.op, exp.Union) and step.distinct:
    359            sink.rows = list(set(left.rows).union(set(right.rows)))
    360        else:
    361            sink.rows = left.rows + right.rows
    362
    363        return self.context({step.name: sink})
    364
    365
    366def _ordered_py(self, expression):
    367    this = self.sql(expression, "this")
    368    desc = "True" if expression.args.get("desc") else "False"
    369    nulls_first = "True" if expression.args.get("nulls_first") else "False"
    370    return f"ORDERED({this}, {desc}, {nulls_first})"
    371
    372
    373def _rename(self, e):
    374    try:
    375        if "expressions" in e.args:
    376            this = self.sql(e, "this")
    377            this = f"{this}, " if this else ""
    378            return f"{e.key.upper()}({this}{self.expressions(e)})"
    379        return self.func(e.key, *e.args.values())
    380    except Exception as ex:
    381        raise Exception(f"Could not rename {repr(e)}") from ex
    382
    383
    384def _case_sql(self, expression):
    385    this = self.sql(expression, "this")
    386    chain = self.sql(expression, "default") or "None"
    387
    388    for e in reversed(expression.args["ifs"]):
    389        true = self.sql(e, "true")
    390        condition = self.sql(e, "this")
    391        condition = f"{this} = ({condition})" if this else condition
    392        chain = f"{true} if {condition} else ({chain})"
    393
    394    return chain
    395
    396
    397def _lambda_sql(self, e: exp.Lambda) -> str:
    398    names = {e.name.lower() for e in e.expressions}
    399
    400    e = e.transform(
    401        lambda n: exp.Var(this=n.name)
    402        if isinstance(n, exp.Identifier) and n.name.lower() in names
    403        else n
    404    )
    405
    406    return f"lambda {self.expressions(e, flat=True)}: {self.sql(e, 'this')}"
    407
    408
    409class Python(Dialect):
    410    class Tokenizer(tokens.Tokenizer):
    411        STRING_ESCAPES = ["\\"]
    412
    413    class Generator(generator.Generator):
    414        TRANSFORMS = {
    415            **{klass: _rename for klass in subclasses(exp.__name__, exp.Binary)},
    416            **{klass: _rename for klass in exp.ALL_FUNCTIONS},
    417            exp.Case: _case_sql,
    418            exp.Alias: lambda self, e: self.sql(e.this),
    419            exp.Array: inline_array_sql,
    420            exp.And: lambda self, e: self.binary(e, "and"),
    421            exp.Between: _rename,
    422            exp.Boolean: lambda self, e: "True" if e.this else "False",
    423            exp.Cast: lambda self, e: f"CAST({self.sql(e.this)}, exp.DataType.Type.{e.args['to']})",
    424            exp.Column: lambda self, e: f"scope[{self.sql(e, 'table') or None}][{self.sql(e.this)}]",
    425            exp.Distinct: lambda self, e: f"set({self.sql(e, 'this')})",
    426            exp.Extract: lambda self, e: f"EXTRACT('{e.name.lower()}', {self.sql(e, 'expression')})",
    427            exp.In: lambda self, e: f"{self.sql(e, 'this')} in ({self.expressions(e, flat=True)})",
    428            exp.Is: lambda self, e: self.binary(e, "is"),
    429            exp.Lambda: _lambda_sql,
    430            exp.Not: lambda self, e: f"not {self.sql(e.this)}",
    431            exp.Null: lambda *_: "None",
    432            exp.Or: lambda self, e: self.binary(e, "or"),
    433            exp.Ordered: _ordered_py,
    434            exp.Star: lambda *_: "1",
    435        }

class PythonExecutor: View Source

     16class PythonExecutor:
     17    def __init__(self, env=None, tables=None):
     18        self.generator = Python().generator(identify=True, comments=False)
     19        self.env = {**ENV, **(env or {})}
     20        self.tables = tables or {}
     21
     22    def execute(self, plan):
     23        running = set()
     24        finished = set()
     25        queue = set(plan.leaves)
     26        contexts = {}
     27
     28        while queue:
     29            node = queue.pop()
     30            try:
     31                context = self.context(
     32                    {
     33                        name: table
     34                        for dep in node.dependencies
     35                        for name, table in contexts[dep].tables.items()
     36                    }
     37                )
     38                running.add(node)
     39
     40                if isinstance(node, planner.Scan):
     41                    contexts[node] = self.scan(node, context)
     42                elif isinstance(node, planner.Aggregate):
     43                    contexts[node] = self.aggregate(node, context)
     44                elif isinstance(node, planner.Join):
     45                    contexts[node] = self.join(node, context)
     46                elif isinstance(node, planner.Sort):
     47                    contexts[node] = self.sort(node, context)
     48                elif isinstance(node, planner.SetOperation):
     49                    contexts[node] = self.set_operation(node, context)
     50                else:
     51                    raise NotImplementedError
     52
     53                running.remove(node)
     54                finished.add(node)
     55
     56                for dep in node.dependents:
     57                    if dep not in running and all(d in contexts for d in dep.dependencies):
     58                        queue.add(dep)
     59
     60                for dep in node.dependencies:
     61                    if all(d in finished for d in dep.dependents):
     62                        contexts.pop(dep)
     63            except Exception as e:
     64                raise ExecuteError(f"Step '{node.id}' failed: {e}") from e
     65
     66        root = plan.root
     67        return contexts[root].tables[root.name]
     68
     69    def generate(self, expression):
     70        """Convert a SQL expression into literal Python code and compile it into bytecode."""
     71        if not expression:
     72            return None
     73
     74        sql = self.generator.generate(expression)
     75        return compile(sql, sql, "eval", optimize=2)
     76
     77    def generate_tuple(self, expressions):
     78        """Convert an array of SQL expressions into tuple of Python byte code."""
     79        if not expressions:
     80            return tuple()
     81        return tuple(self.generate(expression) for expression in expressions)
     82
     83    def context(self, tables):
     84        return Context(tables, env=self.env)
     85
     86    def table(self, expressions):
     87        return Table(
     88            expression.alias_or_name if isinstance(expression, exp.Expression) else expression
     89            for expression in expressions
     90        )
     91
     92    def scan(self, step, context):
     93        source = step.source
     94
     95        if source and isinstance(source, exp.Expression):
     96            source = source.name or source.alias
     97
     98        condition = self.generate(step.condition)
     99        projections = self.generate_tuple(step.projections)
    100
    101        if source is None:
    102            context, table_iter = self.static()
    103        elif source in context:
    104            if not projections and not condition:
    105                return self.context({step.name: context.tables[source]})
    106            table_iter = context.table_iter(source)
    107        elif isinstance(step.source, exp.Table) and isinstance(step.source.this, exp.ReadCSV):
    108            table_iter = self.scan_csv(step)
    109            context = next(table_iter)
    110        else:
    111            context, table_iter = self.scan_table(step)
    112
    113        if projections:
    114            sink = self.table(step.projections)
    115        else:
    116            sink = self.table(context.columns)
    117
    118        for reader in table_iter:
    119            if len(sink) >= step.limit:
    120                break
    121
    122            if condition and not context.eval(condition):
    123                continue
    124
    125            if projections:
    126                sink.append(context.eval_tuple(projections))
    127            else:
    128                sink.append(reader.row)
    129
    130        return self.context({step.name: sink})
    131
    132    def static(self):
    133        return self.context({}), [RowReader(())]
    134
    135    def scan_table(self, step):
    136        table = self.tables.find(step.source)
    137        context = self.context({step.source.alias_or_name: table})
    138        return context, iter(table)
    139
    140    def scan_csv(self, step):
    141        alias = step.source.alias
    142        source = step.source.this
    143
    144        with csv_reader(source) as reader:
    145            columns = next(reader)
    146            table = Table(columns)
    147            context = self.context({alias: table})
    148            yield context
    149            types = []
    150
    151            for row in reader:
    152                if not types:
    153                    for v in row:
    154                        try:
    155                            types.append(type(ast.literal_eval(v)))
    156                        except (ValueError, SyntaxError):
    157                            types.append(str)
    158                context.set_row(tuple(t(v) for t, v in zip(types, row)))
    159                yield context.table.reader
    160
    161    def join(self, step, context):
    162        source = step.name
    163
    164        source_table = context.tables[source]
    165        source_context = self.context({source: source_table})
    166        column_ranges = {source: range(0, len(source_table.columns))}
    167
    168        for name, join in step.joins.items():
    169            table = context.tables[name]
    170            start = max(r.stop for r in column_ranges.values())
    171            column_ranges[name] = range(start, len(table.columns) + start)
    172            join_context = self.context({name: table})
    173
    174            if join.get("source_key"):
    175                table = self.hash_join(join, source_context, join_context)
    176            else:
    177                table = self.nested_loop_join(join, source_context, join_context)
    178
    179            source_context = self.context(
    180                {
    181                    name: Table(table.columns, table.rows, column_range)
    182                    for name, column_range in column_ranges.items()
    183                }
    184            )
    185            condition = self.generate(join["condition"])
    186            if condition:
    187                source_context.filter(condition)
    188
    189        condition = self.generate(step.condition)
    190        projections = self.generate_tuple(step.projections)
    191
    192        if not condition and not projections:
    193            return source_context
    194
    195        sink = self.table(step.projections if projections else source_context.columns)
    196
    197        for reader, ctx in source_context:
    198            if condition and not ctx.eval(condition):
    199                continue
    200
    201            if projections:
    202                sink.append(ctx.eval_tuple(projections))
    203            else:
    204                sink.append(reader.row)
    205
    206            if len(sink) >= step.limit:
    207                break
    208
    209        if projections:
    210            return self.context({step.name: sink})
    211        else:
    212            return self.context(
    213                {
    214                    name: Table(table.columns, sink.rows, table.column_range)
    215                    for name, table in source_context.tables.items()
    216                }
    217            )
    218
    219    def nested_loop_join(self, _join, source_context, join_context):
    220        table = Table(source_context.columns + join_context.columns)
    221
    222        for reader_a, _ in source_context:
    223            for reader_b, _ in join_context:
    224                table.append(reader_a.row + reader_b.row)
    225
    226        return table
    227
    228    def hash_join(self, join, source_context, join_context):
    229        source_key = self.generate_tuple(join["source_key"])
    230        join_key = self.generate_tuple(join["join_key"])
    231        left = join.get("side") == "LEFT"
    232        right = join.get("side") == "RIGHT"
    233
    234        results = collections.defaultdict(lambda: ([], []))
    235
    236        for reader, ctx in source_context:
    237            results[ctx.eval_tuple(source_key)][0].append(reader.row)
    238        for reader, ctx in join_context:
    239            results[ctx.eval_tuple(join_key)][1].append(reader.row)
    240
    241        table = Table(source_context.columns + join_context.columns)
    242        nulls = [(None,) * len(join_context.columns if left else source_context.columns)]
    243
    244        for a_group, b_group in results.values():
    245            if left:
    246                b_group = b_group or nulls
    247            elif right:
    248                a_group = a_group or nulls
    249
    250            for a_row, b_row in itertools.product(a_group, b_group):
    251                table.append(a_row + b_row)
    252
    253        return table
    254
    255    def aggregate(self, step, context):
    256        group_by = self.generate_tuple(step.group.values())
    257        aggregations = self.generate_tuple(step.aggregations)
    258        operands = self.generate_tuple(step.operands)
    259
    260        if operands:
    261            operand_table = Table(self.table(step.operands).columns)
    262
    263            for reader, ctx in context:
    264                operand_table.append(ctx.eval_tuple(operands))
    265
    266            for i, (a, b) in enumerate(zip(context.table.rows, operand_table.rows)):
    267                context.table.rows[i] = a + b
    268
    269            width = len(context.columns)
    270            context.add_columns(*operand_table.columns)
    271
    272            operand_table = Table(
    273                context.columns,
    274                context.table.rows,
    275                range(width, width + len(operand_table.columns)),
    276            )
    277
    278            context = self.context(
    279                {
    280                    None: operand_table,
    281                    **context.tables,
    282                }
    283            )
    284
    285        context.sort(group_by)
    286
    287        group = None
    288        start = 0
    289        end = 1
    290        length = len(context.table)
    291        table = self.table(list(step.group) + step.aggregations)
    292        condition = self.generate(step.condition)
    293
    294        def add_row():
    295            if not condition or context.eval(condition):
    296                table.append(group + context.eval_tuple(aggregations))
    297
    298        if length:
    299            for i in range(length):
    300                context.set_index(i)
    301                key = context.eval_tuple(group_by)
    302                group = key if group is None else group
    303                end += 1
    304                if key != group:
    305                    context.set_range(start, end - 2)
    306                    add_row()
    307                    group = key
    308                    start = end - 2
    309                if len(table.rows) >= step.limit:
    310                    break
    311                if i == length - 1:
    312                    context.set_range(start, end - 1)
    313                    add_row()
    314        elif step.limit > 0 and not group_by:
    315            context.set_range(0, 0)
    316            table.append(context.eval_tuple(aggregations))
    317
    318        context = self.context({step.name: table, **{name: table for name in context.tables}})
    319
    320        if step.projections:
    321            return self.scan(step, context)
    322        return context
    323
    324    def sort(self, step, context):
    325        projections = self.generate_tuple(step.projections)
    326        projection_columns = [p.alias_or_name for p in step.projections]
    327        all_columns = list(context.columns) + projection_columns
    328        sink = self.table(all_columns)
    329        for reader, ctx in context:
    330            sink.append(reader.row + ctx.eval_tuple(projections))
    331
    332        sort_ctx = self.context(
    333            {
    334                None: sink,
    335                **{table: sink for table in context.tables},
    336            }
    337        )
    338        sort_ctx.sort(self.generate_tuple(step.key))
    339
    340        if not math.isinf(step.limit):
    341            sort_ctx.table.rows = sort_ctx.table.rows[0 : step.limit]
    342
    343        output = Table(
    344            projection_columns,
    345            rows=[r[len(context.columns) : len(all_columns)] for r in sort_ctx.table.rows],
    346        )
    347        return self.context({step.name: output})
    348
    349    def set_operation(self, step, context):
    350        left = context.tables[step.left]
    351        right = context.tables[step.right]
    352
    353        sink = self.table(left.columns)
    354
    355        if issubclass(step.op, exp.Intersect):
    356            sink.rows = list(set(left.rows).intersection(set(right.rows)))
    357        elif issubclass(step.op, exp.Except):
    358            sink.rows = list(set(left.rows).difference(set(right.rows)))
    359        elif issubclass(step.op, exp.Union) and step.distinct:
    360            sink.rows = list(set(left.rows).union(set(right.rows)))
    361        else:
    362            sink.rows = left.rows + right.rows
    363
    364        return self.context({step.name: sink})

PythonExecutor(env=None, tables=None) View Source

    17    def __init__(self, env=None, tables=None):
    18        self.generator = Python().generator(identify=True, comments=False)
    19        self.env = {**ENV, **(env or {})}
    20        self.tables = tables or {}

def execute(self, plan): View Source

    22    def execute(self, plan):
    23        running = set()
    24        finished = set()
    25        queue = set(plan.leaves)
    26        contexts = {}
    27
    28        while queue:
    29            node = queue.pop()
    30            try:
    31                context = self.context(
    32                    {
    33                        name: table
    34                        for dep in node.dependencies
    35                        for name, table in contexts[dep].tables.items()
    36                    }
    37                )
    38                running.add(node)
    39
    40                if isinstance(node, planner.Scan):
    41                    contexts[node] = self.scan(node, context)
    42                elif isinstance(node, planner.Aggregate):
    43                    contexts[node] = self.aggregate(node, context)
    44                elif isinstance(node, planner.Join):
    45                    contexts[node] = self.join(node, context)
    46                elif isinstance(node, planner.Sort):
    47                    contexts[node] = self.sort(node, context)
    48                elif isinstance(node, planner.SetOperation):
    49                    contexts[node] = self.set_operation(node, context)
    50                else:
    51                    raise NotImplementedError
    52
    53                running.remove(node)
    54                finished.add(node)
    55
    56                for dep in node.dependents:
    57                    if dep not in running and all(d in contexts for d in dep.dependencies):
    58                        queue.add(dep)
    59
    60                for dep in node.dependencies:
    61                    if all(d in finished for d in dep.dependents):
    62                        contexts.pop(dep)
    63            except Exception as e:
    64                raise ExecuteError(f"Step '{node.id}' failed: {e}") from e
    65
    66        root = plan.root
    67        return contexts[root].tables[root.name]

def generate(self, expression): View Source

    69    def generate(self, expression):
    70        """Convert a SQL expression into literal Python code and compile it into bytecode."""
    71        if not expression:
    72            return None
    73
    74        sql = self.generator.generate(expression)
    75        return compile(sql, sql, "eval", optimize=2)

Convert a SQL expression into literal Python code and compile it into bytecode.

def generate_tuple(self, expressions): View Source

    77    def generate_tuple(self, expressions):
    78        """Convert an array of SQL expressions into tuple of Python byte code."""
    79        if not expressions:
    80            return tuple()
    81        return tuple(self.generate(expression) for expression in expressions)

Convert an array of SQL expressions into tuple of Python byte code.

def context(self, tables): View Source

    83    def context(self, tables):
    84        return Context(tables, env=self.env)

def table(self, expressions): View Source

    86    def table(self, expressions):
    87        return Table(
    88            expression.alias_or_name if isinstance(expression, exp.Expression) else expression
    89            for expression in expressions
    90        )

def scan(self, step, context): View Source

     92    def scan(self, step, context):
     93        source = step.source
     94
     95        if source and isinstance(source, exp.Expression):
     96            source = source.name or source.alias
     97
     98        condition = self.generate(step.condition)
     99        projections = self.generate_tuple(step.projections)
    100
    101        if source is None:
    102            context, table_iter = self.static()
    103        elif source in context:
    104            if not projections and not condition:
    105                return self.context({step.name: context.tables[source]})
    106            table_iter = context.table_iter(source)
    107        elif isinstance(step.source, exp.Table) and isinstance(step.source.this, exp.ReadCSV):
    108            table_iter = self.scan_csv(step)
    109            context = next(table_iter)
    110        else:
    111            context, table_iter = self.scan_table(step)
    112
    113        if projections:
    114            sink = self.table(step.projections)
    115        else:
    116            sink = self.table(context.columns)
    117
    118        for reader in table_iter:
    119            if len(sink) >= step.limit:
    120                break
    121
    122            if condition and not context.eval(condition):
    123                continue
    124
    125            if projections:
    126                sink.append(context.eval_tuple(projections))
    127            else:
    128                sink.append(reader.row)
    129
    130        return self.context({step.name: sink})

def static(self): View Source

    132    def static(self):
    133        return self.context({}), [RowReader(())]

def scan_table(self, step): View Source

    135    def scan_table(self, step):
    136        table = self.tables.find(step.source)
    137        context = self.context({step.source.alias_or_name: table})
    138        return context, iter(table)

def scan_csv(self, step): View Source

    140    def scan_csv(self, step):
    141        alias = step.source.alias
    142        source = step.source.this
    143
    144        with csv_reader(source) as reader:
    145            columns = next(reader)
    146            table = Table(columns)
    147            context = self.context({alias: table})
    148            yield context
    149            types = []
    150
    151            for row in reader:
    152                if not types:
    153                    for v in row:
    154                        try:
    155                            types.append(type(ast.literal_eval(v)))
    156                        except (ValueError, SyntaxError):
    157                            types.append(str)
    158                context.set_row(tuple(t(v) for t, v in zip(types, row)))
    159                yield context.table.reader

def join(self, step, context): View Source

    161    def join(self, step, context):
    162        source = step.name
    163
    164        source_table = context.tables[source]
    165        source_context = self.context({source: source_table})
    166        column_ranges = {source: range(0, len(source_table.columns))}
    167
    168        for name, join in step.joins.items():
    169            table = context.tables[name]
    170            start = max(r.stop for r in column_ranges.values())
    171            column_ranges[name] = range(start, len(table.columns) + start)
    172            join_context = self.context({name: table})
    173
    174            if join.get("source_key"):
    175                table = self.hash_join(join, source_context, join_context)
    176            else:
    177                table = self.nested_loop_join(join, source_context, join_context)
    178
    179            source_context = self.context(
    180                {
    181                    name: Table(table.columns, table.rows, column_range)
    182                    for name, column_range in column_ranges.items()
    183                }
    184            )
    185            condition = self.generate(join["condition"])
    186            if condition:
    187                source_context.filter(condition)
    188
    189        condition = self.generate(step.condition)
    190        projections = self.generate_tuple(step.projections)
    191
    192        if not condition and not projections:
    193            return source_context
    194
    195        sink = self.table(step.projections if projections else source_context.columns)
    196
    197        for reader, ctx in source_context:
    198            if condition and not ctx.eval(condition):
    199                continue
    200
    201            if projections:
    202                sink.append(ctx.eval_tuple(projections))
    203            else:
    204                sink.append(reader.row)
    205
    206            if len(sink) >= step.limit:
    207                break
    208
    209        if projections:
    210            return self.context({step.name: sink})
    211        else:
    212            return self.context(
    213                {
    214                    name: Table(table.columns, sink.rows, table.column_range)
    215                    for name, table in source_context.tables.items()
    216                }
    217            )

def nested_loop_join(self, _join, source_context, join_context): View Source

    219    def nested_loop_join(self, _join, source_context, join_context):
    220        table = Table(source_context.columns + join_context.columns)
    221
    222        for reader_a, _ in source_context:
    223            for reader_b, _ in join_context:
    224                table.append(reader_a.row + reader_b.row)
    225
    226        return table

def hash_join(self, join, source_context, join_context): View Source

    228    def hash_join(self, join, source_context, join_context):
    229        source_key = self.generate_tuple(join["source_key"])
    230        join_key = self.generate_tuple(join["join_key"])
    231        left = join.get("side") == "LEFT"
    232        right = join.get("side") == "RIGHT"
    233
    234        results = collections.defaultdict(lambda: ([], []))
    235
    236        for reader, ctx in source_context:
    237            results[ctx.eval_tuple(source_key)][0].append(reader.row)
    238        for reader, ctx in join_context:
    239            results[ctx.eval_tuple(join_key)][1].append(reader.row)
    240
    241        table = Table(source_context.columns + join_context.columns)
    242        nulls = [(None,) * len(join_context.columns if left else source_context.columns)]
    243
    244        for a_group, b_group in results.values():
    245            if left:
    246                b_group = b_group or nulls
    247            elif right:
    248                a_group = a_group or nulls
    249
    250            for a_row, b_row in itertools.product(a_group, b_group):
    251                table.append(a_row + b_row)
    252
    253        return table

def aggregate(self, step, context): View Source

    255    def aggregate(self, step, context):
    256        group_by = self.generate_tuple(step.group.values())
    257        aggregations = self.generate_tuple(step.aggregations)
    258        operands = self.generate_tuple(step.operands)
    259
    260        if operands:
    261            operand_table = Table(self.table(step.operands).columns)
    262
    263            for reader, ctx in context:
    264                operand_table.append(ctx.eval_tuple(operands))
    265
    266            for i, (a, b) in enumerate(zip(context.table.rows, operand_table.rows)):
    267                context.table.rows[i] = a + b
    268
    269            width = len(context.columns)
    270            context.add_columns(*operand_table.columns)
    271
    272            operand_table = Table(
    273                context.columns,
    274                context.table.rows,
    275                range(width, width + len(operand_table.columns)),
    276            )
    277
    278            context = self.context(
    279                {
    280                    None: operand_table,
    281                    **context.tables,
    282                }
    283            )
    284
    285        context.sort(group_by)
    286
    287        group = None
    288        start = 0
    289        end = 1
    290        length = len(context.table)
    291        table = self.table(list(step.group) + step.aggregations)
    292        condition = self.generate(step.condition)
    293
    294        def add_row():
    295            if not condition or context.eval(condition):
    296                table.append(group + context.eval_tuple(aggregations))
    297
    298        if length:
    299            for i in range(length):
    300                context.set_index(i)
    301                key = context.eval_tuple(group_by)
    302                group = key if group is None else group
    303                end += 1
    304                if key != group:
    305                    context.set_range(start, end - 2)
    306                    add_row()
    307                    group = key
    308                    start = end - 2
    309                if len(table.rows) >= step.limit:
    310                    break
    311                if i == length - 1:
    312                    context.set_range(start, end - 1)
    313                    add_row()
    314        elif step.limit > 0 and not group_by:
    315            context.set_range(0, 0)
    316            table.append(context.eval_tuple(aggregations))
    317
    318        context = self.context({step.name: table, **{name: table for name in context.tables}})
    319
    320        if step.projections:
    321            return self.scan(step, context)
    322        return context

def sort(self, step, context): View Source

    324    def sort(self, step, context):
    325        projections = self.generate_tuple(step.projections)
    326        projection_columns = [p.alias_or_name for p in step.projections]
    327        all_columns = list(context.columns) + projection_columns
    328        sink = self.table(all_columns)
    329        for reader, ctx in context:
    330            sink.append(reader.row + ctx.eval_tuple(projections))
    331
    332        sort_ctx = self.context(
    333            {
    334                None: sink,
    335                **{table: sink for table in context.tables},
    336            }
    337        )
    338        sort_ctx.sort(self.generate_tuple(step.key))
    339
    340        if not math.isinf(step.limit):
    341            sort_ctx.table.rows = sort_ctx.table.rows[0 : step.limit]
    342
    343        output = Table(
    344            projection_columns,
    345            rows=[r[len(context.columns) : len(all_columns)] for r in sort_ctx.table.rows],
    346        )
    347        return self.context({step.name: output})

def set_operation(self, step, context): View Source

    349    def set_operation(self, step, context):
    350        left = context.tables[step.left]
    351        right = context.tables[step.right]
    352
    353        sink = self.table(left.columns)
    354
    355        if issubclass(step.op, exp.Intersect):
    356            sink.rows = list(set(left.rows).intersection(set(right.rows)))
    357        elif issubclass(step.op, exp.Except):
    358            sink.rows = list(set(left.rows).difference(set(right.rows)))
    359        elif issubclass(step.op, exp.Union) and step.distinct:
    360            sink.rows = list(set(left.rows).union(set(right.rows)))
    361        else:
    362            sink.rows = left.rows + right.rows
    363
    364        return self.context({step.name: sink})

class Python(sqlglot.dialects.dialect.Dialect): View Source

    410class Python(Dialect):
    411    class Tokenizer(tokens.Tokenizer):
    412        STRING_ESCAPES = ["\\"]
    413
    414    class Generator(generator.Generator):
    415        TRANSFORMS = {
    416            **{klass: _rename for klass in subclasses(exp.__name__, exp.Binary)},
    417            **{klass: _rename for klass in exp.ALL_FUNCTIONS},
    418            exp.Case: _case_sql,
    419            exp.Alias: lambda self, e: self.sql(e.this),
    420            exp.Array: inline_array_sql,
    421            exp.And: lambda self, e: self.binary(e, "and"),
    422            exp.Between: _rename,
    423            exp.Boolean: lambda self, e: "True" if e.this else "False",
    424            exp.Cast: lambda self, e: f"CAST({self.sql(e.this)}, exp.DataType.Type.{e.args['to']})",
    425            exp.Column: lambda self, e: f"scope[{self.sql(e, 'table') or None}][{self.sql(e.this)}]",
    426            exp.Distinct: lambda self, e: f"set({self.sql(e, 'this')})",
    427            exp.Extract: lambda self, e: f"EXTRACT('{e.name.lower()}', {self.sql(e, 'expression')})",
    428            exp.In: lambda self, e: f"{self.sql(e, 'this')} in ({self.expressions(e, flat=True)})",
    429            exp.Is: lambda self, e: self.binary(e, "is"),
    430            exp.Lambda: _lambda_sql,
    431            exp.Not: lambda self, e: f"not {self.sql(e.this)}",
    432            exp.Null: lambda *_: "None",
    433            exp.Or: lambda self, e: self.binary(e, "or"),
    434            exp.Ordered: _ordered_py,
    435            exp.Star: lambda *_: "1",
    436        }

##### Inherited Members

sqlglot.dialects.dialect.Dialect
  get_or_raise
  format_time
  parse
  parse_into
  generate
  transpile
  parser
  generator

class Python.Tokenizer(sqlglot.tokens.Tokenizer): View Source

    411    class Tokenizer(tokens.Tokenizer):
    412        STRING_ESCAPES = ["\\"]

##### Inherited Members

sqlglot.tokens.Tokenizer
  reset
  tokenize

class Python.Generator(sqlglot.generator.Generator): View Source

    414    class Generator(generator.Generator):
    415        TRANSFORMS = {
    416            **{klass: _rename for klass in subclasses(exp.__name__, exp.Binary)},
    417            **{klass: _rename for klass in exp.ALL_FUNCTIONS},
    418            exp.Case: _case_sql,
    419            exp.Alias: lambda self, e: self.sql(e.this),
    420            exp.Array: inline_array_sql,
    421            exp.And: lambda self, e: self.binary(e, "and"),
    422            exp.Between: _rename,
    423            exp.Boolean: lambda self, e: "True" if e.this else "False",
    424            exp.Cast: lambda self, e: f"CAST({self.sql(e.this)}, exp.DataType.Type.{e.args['to']})",
    425            exp.Column: lambda self, e: f"scope[{self.sql(e, 'table') or None}][{self.sql(e.this)}]",
    426            exp.Distinct: lambda self, e: f"set({self.sql(e, 'this')})",
    427            exp.Extract: lambda self, e: f"EXTRACT('{e.name.lower()}', {self.sql(e, 'expression')})",
    428            exp.In: lambda self, e: f"{self.sql(e, 'this')} in ({self.expressions(e, flat=True)})",
    429            exp.Is: lambda self, e: self.binary(e, "is"),
    430            exp.Lambda: _lambda_sql,
    431            exp.Not: lambda self, e: f"not {self.sql(e.this)}",
    432            exp.Null: lambda *_: "None",
    433            exp.Or: lambda self, e: self.binary(e, "or"),
    434            exp.Ordered: _ordered_py,
    435            exp.Star: lambda *_: "1",
    436        }

Generator interprets the given syntax tree and produces a SQL string as an output.

###### Arguments:

- time_mapping (dict): the dictionary of custom time mappings in which the key represents a python time format and the output the target time format
- time_trie (trie): a trie of the time_mapping keys
- pretty (bool): if set to True the returned string will be formatted. Default: False.
- quote_start (str): specifies which starting character to use to delimit quotes. Default: '.
- quote_end (str): specifies which ending character to use to delimit quotes. Default: '.
- identifier_start (str): specifies which starting character to use to delimit identifiers. Default: ".
- identifier_end (str): specifies which ending character to use to delimit identifiers. Default: ".
- identify (bool): if set to True all identifiers will be delimited by the corresponding character.
- normalize (bool): if set to True all identifiers will lower cased
- string_escape (str): specifies a string escape character. Default: '.
- identifier_escape (str): specifies an identifier escape character. Default: ".
- pad (int): determines padding in a formatted string. Default: 2.
- indent (int): determines the size of indentation in a formatted string. Default: 4.
- unnest_column_only (bool): if true unnest table aliases are considered only as column aliases
- normalize_functions (str): normalize function names, "upper", "lower", or None Default: "upper"
- alias_post_tablesample (bool): if the table alias comes after tablesample Default: False
- unsupported_level (ErrorLevel): determines the generator's behavior when it encounters unsupported expressions. Default ErrorLevel.WARN.
- null_ordering (str): Indicates the default null ordering method to use if not explicitly set. Options are "nulls_are_small", "nulls_are_large", "nulls_are_last". Default: "nulls_are_small"
- max_unsupported (int): Maximum number of unsupported messages to include in a raised UnsupportedError. This is only relevant if unsupported_level is ErrorLevel.RAISE. Default: 3
- leading_comma (bool): if the the comma is leading or trailing in select statements Default: False
- max_text_width: The max number of characters in a segment before creating new lines in pretty mode. The default is on the smaller end because the length only represents a segment and not the true line length. Default: 80
- comments: Whether or not to preserve comments in the output SQL code. Default: True

##### Inherited Members

sqlglot.generator.Generator
  Generator
  generate
  unsupported
  sep
  seg
  pad_comment
  maybe_comment
  wrap
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