src/backend/parser/README

Parser

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This directory does more than tokenize and parse SQL queries. It also

creates Query structures for the various complex queries that are passed

to the optimizer and then executor.

parser.c things start here

scan.l break query into tokens

scansup.c handle escapes in input strings

gram.y parse the tokens and produce a "raw" parse tree

analyze.c top level of parse analysis for optimizable queries

parse_agg.c handle aggregates, like SUM(col1), AVG(col2), ...

parse_clause.c handle clauses like WHERE, ORDER BY, GROUP BY, ...

parse_coerce.c handle coercing expressions to different data types

parse_collate.c assign collation information in completed expressions

parse_cte.c handle Common Table Expressions (WITH clauses)

parse_expr.c handle expressions like col, col + 3, x = 3 or x = 4

parse_enr.c handle ephemeral named rels (trigger transition tables, ...)

parse_func.c handle functions, table.column and column identifiers

parse_jsontable.c handle JSON_TABLE

parse_merge.c handle MERGE

parse_node.c create nodes for various structures

parse_oper.c handle operators in expressions

parse_param.c handle Params (for the cases used in the core backend)

parse_relation.c support routines for tables and column handling

parse_target.c handle the result list of the query

parse_type.c support routines for data type handling

parse_utilcmd.c parse analysis for utility commands (done at execution time)

See also src/common/keywords.c, which contains the table of standard

keywords and the keyword lookup function. We separated that out because

various frontend code wants to use it too.