queryjumble.h

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/*-------------------------------------------------------------------------
 *
 * queryjumble.h
 *    Query normalization and fingerprinting.
 *
 * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * IDENTIFICATION
 *    src/include/nodes/queryjumble.h
 *
 *-------------------------------------------------------------------------
 */
#ifndef QUERYJUMBLE_H
#define QUERYJUMBLE_H
 
#include "nodes/parsenodes.h"
 
/*
 * Struct for tracking locations/lengths of constants during normalization
 */
typedef struct LocationLen
{
    int         location;       /* start offset in query text */
    int         length;         /* length in bytes, or -1 to ignore */
 
    /* Does this location represent a squashed list? */
    bool        squashed;
 
    /* Is this location a PARAM_EXTERN parameter? */
    bool        extern_param;
} LocationLen;
 
/*
 * Working state for computing a query jumble and producing a normalized
 * query string
 */
typedef struct JumbleState
{
    /* Jumble of current query tree */
    unsigned char *jumble;
 
    /* Number of bytes used in jumble[] */
    Size        jumble_len;
 
    /* Array of locations of constants that should be removed */
    LocationLen *clocations;
 
    /* Allocated length of clocations array */
    int         clocations_buf_size;
 
    /* Current number of valid entries in clocations array */
    int         clocations_count;
 
    /*
     * ID of the highest PARAM_EXTERN parameter we've seen in the query; used
     * to start normalization correctly.  However, if there are any squashed
     * lists in the query, we disregard query-supplied parameter numbers and
     * renumber everything.  This is to avoid possible gaps caused by
     * squashing in case any params are in squashed lists.
     */
    int         highest_extern_param_id;
 
    /* Whether squashable lists are present */
    bool        has_squashed_lists;
 
    /*
     * Count of the number of NULL nodes seen since last appending a value.
     * These are flushed out to the jumble buffer before subsequent appends
     * and before performing the final jumble hash.
     */
    unsigned int pending_nulls;
 
#ifdef USE_ASSERT_CHECKING
    /* The total number of bytes added to the jumble buffer */
    Size        total_jumble_len;
#endif
} JumbleState;
 
/* Values for the compute_query_id GUC */
enum ComputeQueryIdType
{
    COMPUTE_QUERY_ID_OFF,
    COMPUTE_QUERY_ID_ON,
    COMPUTE_QUERY_ID_AUTO,
    COMPUTE_QUERY_ID_REGRESS,
};
 
/* GUC parameters */
extern PGDLLIMPORT int compute_query_id;
 
 
extern const char *CleanQuerytext(const char *query, int *location, int *len);
extern JumbleState *JumbleQuery(Query *query);
extern void EnableQueryId(void);
 
extern PGDLLIMPORT bool query_id_enabled;
 
/*
 * Returns whether query identifier computation has been enabled, either
 * directly in the GUC or by a module when the setting is 'auto'.
 */
static inline bool
IsQueryIdEnabled(void)
{
    if (compute_query_id == COMPUTE_QUERY_ID_OFF)
        return false;
    if (compute_query_id == COMPUTE_QUERY_ID_ON)
        return true;
    return query_id_enabled;
}
 
#endif                          /* QUERYJUMBLE_H */