sqlglot.optimizer.qualify API documentation

Edit on GitHub

# sqlglot.optimizer.qualify

View Source

      1from __future__ import annotations
      2
      3import typing as t
      4
      5from sqlglot import exp
      6from sqlglot.dialects.dialect import Dialect, DialectType
      7from sqlglot.optimizer.isolate_table_selects import isolate_table_selects
      8from sqlglot.optimizer.normalize_identifiers import normalize_identifiers
      9from sqlglot.optimizer.qualify_columns import (
     10    pushdown_cte_alias_columns as pushdown_cte_alias_columns_func,
     11    qualify_columns as qualify_columns_func,
     12    quote_identifiers as quote_identifiers_func,
     13    validate_qualify_columns as validate_qualify_columns_func,
     14)
     15from sqlglot.optimizer.qualify_tables import qualify_tables
     16from sqlglot.schema import Schema, ensure_schema
     17
     18
     19def qualify(
     20    expression: exp.Expression,
     21    dialect: DialectType = None,
     22    db: t.Optional[str] = None,
     23    catalog: t.Optional[str] = None,
     24    schema: t.Optional[dict | Schema] = None,
     25    expand_alias_refs: bool = True,
     26    expand_stars: bool = True,
     27    infer_schema: t.Optional[bool] = None,
     28    isolate_tables: bool = False,
     29    qualify_columns: bool = True,
     30    allow_partial_qualification: bool = False,
     31    validate_qualify_columns: bool = True,
     32    quote_identifiers: bool = True,
     33    identify: bool = True,
     34    infer_csv_schemas: bool = False,
     35) -> exp.Expression:
     36    """
     37    Rewrite sqlglot AST to have normalized and qualified tables and columns.
     38
     39    This step is necessary for all further SQLGlot optimizations.
     40
     41    Example:
     42        >>> import sqlglot
     43        >>> schema = {"tbl": {"col": "INT"}}
     44        >>> expression = sqlglot.parse_one("SELECT col FROM tbl")
     45        >>> qualify(expression, schema=schema).sql()
     46        'SELECT "tbl"."col" AS "col" FROM "tbl" AS "tbl"'
     47
     48    Args:
     49        expression: Expression to qualify.
     50        db: Default database name for tables.
     51        catalog: Default catalog name for tables.
     52        schema: Schema to infer column names and types.
     53        expand_alias_refs: Whether to expand references to aliases.
     54        expand_stars: Whether to expand star queries. This is a necessary step
     55            for most of the optimizer's rules to work; do not set to False unless you
     56            know what you're doing!
     57        infer_schema: Whether to infer the schema if missing.
     58        isolate_tables: Whether to isolate table selects.
     59        qualify_columns: Whether to qualify columns.
     60        allow_partial_qualification: Whether to allow partial qualification.
     61        validate_qualify_columns: Whether to validate columns.
     62        quote_identifiers: Whether to run the quote_identifiers step.
     63            This step is necessary to ensure correctness for case sensitive queries.
     64            But this flag is provided in case this step is performed at a later time.
     65        identify: If True, quote all identifiers, else only necessary ones.
     66        infer_csv_schemas: Whether to scan READ_CSV calls in order to infer the CSVs' schemas.
     67
     68    Returns:
     69        The qualified expression.
     70    """
     71    schema = ensure_schema(schema, dialect=dialect)
     72    expression = qualify_tables(
     73        expression,
     74        db=db,
     75        catalog=catalog,
     76        schema=schema,
     77        dialect=dialect,
     78        infer_csv_schemas=infer_csv_schemas,
     79    )
     80    expression = normalize_identifiers(expression, dialect=dialect)
     81
     82    if isolate_tables:
     83        expression = isolate_table_selects(expression, schema=schema)
     84
     85    if Dialect.get_or_raise(dialect).PREFER_CTE_ALIAS_COLUMN:
     86        expression = pushdown_cte_alias_columns_func(expression)
     87
     88    if qualify_columns:
     89        expression = qualify_columns_func(
     90            expression,
     91            schema,
     92            expand_alias_refs=expand_alias_refs,
     93            expand_stars=expand_stars,
     94            infer_schema=infer_schema,
     95            allow_partial_qualification=allow_partial_qualification,
     96        )
     97
     98    if quote_identifiers:
     99        expression = quote_identifiers_func(expression, dialect=dialect, identify=identify)
    100
    101    if validate_qualify_columns:
    102        validate_qualify_columns_func(expression)
    103
    104    return expression

def qualify( expression: sqlglot.expressions.Expression, dialect: Union[str, sqlglot.dialects.dialect.Dialect, Type[sqlglot.dialects.dialect.Dialect], NoneType] = None, db: Optional[str] = None, catalog: Optional[str] = None, schema: Union[dict, sqlglot.schema.Schema, NoneType] = None, expand_alias_refs: bool = True, expand_stars: bool = True, infer_schema: Optional[bool] = None, isolate_tables: bool = False, qualify_columns: bool = True, allow_partial_qualification: bool = False, validate_qualify_columns: bool = True, quote_identifiers: bool = True, identify: bool = True, infer_csv_schemas: bool = False) -> sqlglot.expressions.Expression: View Source

     20def qualify(
     21    expression: exp.Expression,
     22    dialect: DialectType = None,
     23    db: t.Optional[str] = None,
     24    catalog: t.Optional[str] = None,
     25    schema: t.Optional[dict | Schema] = None,
     26    expand_alias_refs: bool = True,
     27    expand_stars: bool = True,
     28    infer_schema: t.Optional[bool] = None,
     29    isolate_tables: bool = False,
     30    qualify_columns: bool = True,
     31    allow_partial_qualification: bool = False,
     32    validate_qualify_columns: bool = True,
     33    quote_identifiers: bool = True,
     34    identify: bool = True,
     35    infer_csv_schemas: bool = False,
     36) -> exp.Expression:
     37    """
     38    Rewrite sqlglot AST to have normalized and qualified tables and columns.
     39
     40    This step is necessary for all further SQLGlot optimizations.
     41
     42    Example:
     43        >>> import sqlglot
     44        >>> schema = {"tbl": {"col": "INT"}}
     45        >>> expression = sqlglot.parse_one("SELECT col FROM tbl")
     46        >>> qualify(expression, schema=schema).sql()
     47        'SELECT "tbl"."col" AS "col" FROM "tbl" AS "tbl"'
     48
     49    Args:
     50        expression: Expression to qualify.
     51        db: Default database name for tables.
     52        catalog: Default catalog name for tables.
     53        schema: Schema to infer column names and types.
     54        expand_alias_refs: Whether to expand references to aliases.
     55        expand_stars: Whether to expand star queries. This is a necessary step
     56            for most of the optimizer's rules to work; do not set to False unless you
     57            know what you're doing!
     58        infer_schema: Whether to infer the schema if missing.
     59        isolate_tables: Whether to isolate table selects.
     60        qualify_columns: Whether to qualify columns.
     61        allow_partial_qualification: Whether to allow partial qualification.
     62        validate_qualify_columns: Whether to validate columns.
     63        quote_identifiers: Whether to run the quote_identifiers step.
     64            This step is necessary to ensure correctness for case sensitive queries.
     65            But this flag is provided in case this step is performed at a later time.
     66        identify: If True, quote all identifiers, else only necessary ones.
     67        infer_csv_schemas: Whether to scan READ_CSV calls in order to infer the CSVs' schemas.
     68
     69    Returns:
     70        The qualified expression.
     71    """
     72    schema = ensure_schema(schema, dialect=dialect)
     73    expression = qualify_tables(
     74        expression,
     75        db=db,
     76        catalog=catalog,
     77        schema=schema,
     78        dialect=dialect,
     79        infer_csv_schemas=infer_csv_schemas,
     80    )
     81    expression = normalize_identifiers(expression, dialect=dialect)
     82
     83    if isolate_tables:
     84        expression = isolate_table_selects(expression, schema=schema)
     85
     86    if Dialect.get_or_raise(dialect).PREFER_CTE_ALIAS_COLUMN:
     87        expression = pushdown_cte_alias_columns_func(expression)
     88
     89    if qualify_columns:
     90        expression = qualify_columns_func(
     91            expression,
     92            schema,
     93            expand_alias_refs=expand_alias_refs,
     94            expand_stars=expand_stars,
     95            infer_schema=infer_schema,
     96            allow_partial_qualification=allow_partial_qualification,
     97        )
     98
     99    if quote_identifiers:
    100        expression = quote_identifiers_func(expression, dialect=dialect, identify=identify)
    101
    102    if validate_qualify_columns:
    103        validate_qualify_columns_func(expression)
    104
    105    return expression

Rewrite sqlglot AST to have normalized and qualified tables and columns.

This step is necessary for all further SQLGlot optimizations.

###### Example:

>     >>> import sqlglot
>     >>> schema = {"tbl": {"col": "INT"}}
>     >>> expression = sqlglot.parse_one("SELECT col FROM tbl")
>     >>> qualify(expression, schema=schema).sql()
>     'SELECT "tbl"."col" AS "col" FROM "tbl" AS "tbl"'

###### Arguments:

- expression: Expression to qualify.
- db: Default database name for tables.
- catalog: Default catalog name for tables.
- schema: Schema to infer column names and types.
- expand_alias_refs: Whether to expand references to aliases.
- expand_stars: Whether to expand star queries. This is a necessary step for most of the optimizer's rules to work; do not set to False unless you know what you're doing!
- infer_schema: Whether to infer the schema if missing.
- isolate_tables: Whether to isolate table selects.
- qualify_columns: Whether to qualify columns.
- allow_partial_qualification: Whether to allow partial qualification.
- validate_qualify_columns: Whether to validate columns.
- quote_identifiers: Whether to run the quote_identifiers step. This step is necessary to ensure correctness for case sensitive queries. But this flag is provided in case this step is performed at a later time.
- identify: If True, quote all identifiers, else only necessary ones.
- infer_csv_schemas: Whether to scan READ_CSV calls in order to infer the CSVs' schemas.

###### Returns:

> The qualified expression.