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postgres/src/backend/parser
Álvaro Herrera 0f65f3eec4 Fix squashing algorithm for query texts
The algorithm to squash lists of constants added by commit 62d712ecfd
was a bit too simplistic; we wanted to avoid adding unnecessary
complexity, but cases like direct function calls of typecasting
functions (and others) were missed, and bogus SQL syntax was being shown
in pg_stat_statements normalized query text field.  To fix normalization
for those cases, we need the parser to transmit information about were
each list of constant values starts and ends, so add that to a couple of
nodes.  Also add a few more test cases to make sure we're doing the
right thing.

The patch initially submitted by Sami added a new private struct in
gram.y to carry the start/end information for A_Expr, but I (Álvaro)
decided that a better fix was to remove the parser indirection via the
in_expr production, and instead create separate components in the a_expr
rule.  I'm surprised that this works and doesn't require more changes,
but I assume (without checking) that the grammar used to be more complex
and got simplified at some point.

Bump catversion.

Author: Sami Imseih <samimseih@gmail.com>
Author: Dmitry Dolgov <9erthalion6@gmail.com>
Reviewed-by: Michael Paquier <michael@paquier.xyz>
Discussion: https://postgr.es/m/CAA5RZ0tRXoPG2y6bMgBCWNDt0Tn=unRerbzYM=oW0syi1=C1OA@mail.gmail.com
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src/backend/parser/README

Parser
======

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_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.