Revert support for improved tracking of nested queries

This commit reverts the two following commits:
- 499edb09741b, track more precisely query locations for nested
statements.
- 06450c7b8c70, a follow-up fix of 499edb09741b with query locations.
The test introduced in this commit is not reverted.  This is proving
useful to track a problem that only pgaudit was able to detect.

These prove to have issues with the tracking of SELECT statements, when
these use multiple parenthesis which is something supported by the
grammar.  Incorrect location and lengths are causing pg_stat_statements
to become confused, failing its job in query normalization with
potential out-of-bound writes because the location and the length may
not match with what can be handled.  A lot of the query patterns
discussed when this issue was reported have no test coverage in the main
regression test suite, or the recovery test 027_stream_regress.pl would
have caught the problems as pg_stat_statements is loaded by the node
running the regression tests.  A first step would be to improve the test
coverage to stress more the query normalization logic.

A different portion of this work was done in 45e0ba30fc40, with the
addition of tests for nested queries.  These can be left in the tree.
They are useful to track the way inner queries are currently tracked by
PGSS with non-top-level entries, and will be useful when reconsidering
in the future the work reverted here.

Reported-by: Alexander Kozhemyakin <a.kozhemyakin@postgrespro.ru>
Discussion: https://postgr.es/m/18947-cdd2668beffe02bf@postgresql.org

1 files changed, 0 insertions, 16 deletions

diff --git a/src/include/parser/parse_node.h b/src/include/parser/parse_node.h
index 994284019fb..f7d07c84542 100644
--- a/src/include/parser/parse_node.h
+++ b/src/include/parser/parse_node.h
@@ -108,20 +108,6 @@ typedef Node *(*CoerceParamHook) (ParseState *pstate, Param *param,
  * byte-wise locations in parse structures to character-wise cursor
  * positions.)
  *
- * p_stmt_location: location of the top level RawStmt's start.  During
- * transformation, the Query's location will be set to the statement's
- * location if available.  Otherwise, the RawStmt's start location will
- * be used.  Propagating the location through ParseState is needed for
- * the Query length calculation (see p_stmt_len below).
- *
- * p_stmt_len: length of the top level RawStmt.  Most of the time, the
- * statement's length is not provided by the parser, with the exception
- * of SelectStmt within parentheses and PreparableStmt in COPY.  If the
- * statement's location is provided by the parser, the top-level location
- * and length are needed to accurately compute the Query's length.  If the
- * statement's location is not provided, the RawStmt's length can be used
- * directly.
- *
  * p_rtable: list of RTEs that will become the rangetable of the query.
  * Note that neither relname nor refname of these entries are necessarily
  * unique; searching the rtable by name is a bad idea.
@@ -207,8 +193,6 @@ struct ParseState
 {
 	ParseState *parentParseState;	/* stack link */
 	const char *p_sourcetext;	/* source text, or NULL if not available */
-	ParseLoc	p_stmt_location;	/* start location, or -1 if unknown */
-	ParseLoc	p_stmt_len;		/* length in bytes; 0 means "rest of string" */
 	List	   *p_rtable;		/* range table so far */
 	List	   *p_rteperminfos; /* list of RTEPermissionInfo nodes for each
 								 * RTE_RELATION entry in rtable */