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c2da1a5d63
Commit 62d712ecfd made query jumbling squash lists of Consts as a
single element, but there's no reason not to treat PARAM_EXTERN
parameters the same. For these purposes, these values are indeed
constants for any particular execution of a query.
In particular, this should make list squashing more useful for
applications using extended query protocol, which would use parameters
extensively.
A complication arises: if a query has both external parameters and
squashable lists, then the parameter number used as placeholder for the
squashed list might be inconsistent with regards to the parameter
numbers used by the query literal. To reduce the surprise factor, all
parameters are renumbered starting from 1 in that case.
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
114 lines
2.9 KiB
C
114 lines
2.9 KiB
C
/*-------------------------------------------------------------------------
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*
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* queryjumble.h
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* Query normalization and fingerprinting.
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*
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* Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* IDENTIFICATION
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* src/include/nodes/queryjumble.h
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef QUERYJUMBLE_H
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#define QUERYJUMBLE_H
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#include "nodes/parsenodes.h"
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/*
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* Struct for tracking locations/lengths of constants during normalization
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*/
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typedef struct LocationLen
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{
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int location; /* start offset in query text */
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int length; /* length in bytes, or -1 to ignore */
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/* Does this location represent a squashed list? */
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bool squashed;
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/* Is this location a PARAM_EXTERN parameter? */
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bool extern_param;
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} LocationLen;
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/*
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* Working state for computing a query jumble and producing a normalized
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* query string
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*/
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typedef struct JumbleState
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{
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/* Jumble of current query tree */
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unsigned char *jumble;
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/* Number of bytes used in jumble[] */
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Size jumble_len;
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/* Array of locations of constants that should be removed */
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LocationLen *clocations;
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/* Allocated length of clocations array */
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int clocations_buf_size;
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/* Current number of valid entries in clocations array */
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int clocations_count;
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/*
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* ID of the highest PARAM_EXTERN parameter we've seen in the query; used
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* to start normalization correctly. However, if there are any squashed
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* lists in the query, we disregard query-supplied parameter numbers and
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* renumber everything. This is to avoid possible gaps caused by
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* squashing in case any params are in squashed lists.
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*/
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int highest_extern_param_id;
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/* Whether squashable lists are present */
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bool has_squashed_lists;
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/*
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* Count of the number of NULL nodes seen since last appending a value.
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* These are flushed out to the jumble buffer before subsequent appends
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* and before performing the final jumble hash.
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*/
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unsigned int pending_nulls;
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#ifdef USE_ASSERT_CHECKING
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/* The total number of bytes added to the jumble buffer */
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Size total_jumble_len;
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#endif
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} JumbleState;
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/* Values for the compute_query_id GUC */
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enum ComputeQueryIdType
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{
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COMPUTE_QUERY_ID_OFF,
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COMPUTE_QUERY_ID_ON,
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COMPUTE_QUERY_ID_AUTO,
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COMPUTE_QUERY_ID_REGRESS,
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};
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/* GUC parameters */
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extern PGDLLIMPORT int compute_query_id;
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extern const char *CleanQuerytext(const char *query, int *location, int *len);
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extern JumbleState *JumbleQuery(Query *query);
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extern void EnableQueryId(void);
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extern PGDLLIMPORT bool query_id_enabled;
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/*
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* Returns whether query identifier computation has been enabled, either
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* directly in the GUC or by a module when the setting is 'auto'.
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*/
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static inline bool
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IsQueryIdEnabled(void)
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{
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if (compute_query_id == COMPUTE_QUERY_ID_OFF)
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return false;
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if (compute_query_id == COMPUTE_QUERY_ID_ON)
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return true;
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return query_id_enabled;
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}
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#endif /* QUERYJUMBLE_H */
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