/* -------------------------------------------------------------------------

 *

 * pgstat_index.c

 *    Implementation of index statistics.

 *

 * This file contains the implementation of index statistics.

 *

 * Copyright (c) 2001-2026, PostgreSQL Global Development Group

 *

 * IDENTIFICATION

 *    src/backend/utils/activity/pgstat_index.c

 * -------------------------------------------------------------------------

 */

#include "postgres.h"

#include "access/xact.h"

#include "catalog/catalog.h"

#include "utils/memutils.h"

#include "utils/pgstat_internal.h"

#include "utils/rel.h"

#include "utils/timestamp.h"

/*

 * Flush out pending stats for an index entry.

 *

 * If nowait is true and the lock could not be immediately acquired, returns

 * false without flushing the entry.  Otherwise returns true.

 *

 * Some of the stats are copied to the corresponding pending database stats

 * entry when successfully flushing.

 */

bool

pgstat_index_flush_cb(PgStat_EntryRef *entry_ref, bool nowait)

{

  Oid     dboid;

  PgStat_TableStatus *lstats; /* pending stats entry */

  PgStatShared_Index *shidxstats;

  PgStat_StatIdxEntry *idxentry;  /* index entry of shared stats */

  PgStat_StatDBEntry *dbentry;  /* pending database entry */

  dboid = entry_ref->shared_entry->key.dboid;

  lstats = (PgStat_TableStatus *) entry_ref->pending;

  shidxstats = (PgStatShared_Index *) entry_ref->shared_stats;

  /*

   * Ignore entries that didn't accumulate any actual counts, such as

   * indexes that were opened by the planner but not used.

   */

  if (pg_memory_is_all_zeros(&lstats->counts,

                 sizeof(struct PgStat_TableCounts)))

    return true;

  if (!pgstat_lock_entry(entry_ref, nowait))

    return false;

  /* Add the values to the shared entry. */

  idxentry = &shidxstats->stats;

  idxentry->numscans += lstats->counts.numscans;

  if (lstats->counts.numscans)

  {

    TimestampTz t = GetCurrentTransactionStopTimestamp();

    if (t > idxentry->lastscan)

      idxentry->lastscan = t;

  }

  idxentry->tuples_returned += lstats->counts.tuples_returned;

  idxentry->tuples_fetched += lstats->counts.tuples_fetched;

  idxentry->blocks_fetched += lstats->counts.blocks_fetched;

  idxentry->blocks_hit += lstats->counts.blocks_hit;

  pgstat_unlock_entry(entry_ref);

  /* The entry was successfully flushed, add the same to database stats */

  dbentry = pgstat_prep_database_pending(dboid);

  dbentry->tuples_returned += lstats->counts.tuples_returned;

  dbentry->tuples_fetched += lstats->counts.tuples_fetched;

  dbentry->blocks_fetched += lstats->counts.blocks_fetched;

  dbentry->blocks_hit += lstats->counts.blocks_hit;

  return true;

}

/*

 * Callback to delete pending index stats.

 */

void

pgstat_index_delete_pending_cb(PgStat_EntryRef *entry_ref)

{

  PgStat_TableStatus *pending = (PgStat_TableStatus *) entry_ref->pending;

  if (pending->relation)

    pgstat_unlink_relation(pending->relation);

}

/*

 * Callback to reset the timestamp on an index stats entry.

 */

void

pgstat_index_reset_timestamp_cb(PgStatShared_Common *header, TimestampTz ts)

{

  ((PgStatShared_Index *) header)->stats.stat_reset_time = ts;

}

/*

 * Support function for the SQL-callable pgstat* functions. Returns

 * the collected statistics for one index or NULL. NULL doesn't mean

 * that the index doesn't exist, just that there are no statistics, so the

 * caller is better off to report ZERO instead.

 */

PgStat_StatIdxEntry *

pgstat_fetch_stat_idxentry(Oid relid)

{

  return pgstat_fetch_stat_idxentry_ext(IsSharedRelation(relid), relid, NULL);

}

/*

 * More efficient version of pgstat_fetch_stat_idxentry(), allowing to specify

 * whether the to-be-accessed index is a shared relation or not.  This version

 * also returns whether the caller can pfree() the result if desired.

 */

PgStat_StatIdxEntry *

pgstat_fetch_stat_idxentry_ext(bool shared, Oid reloid, bool *may_free)

{

  Oid     dboid = (shared ? InvalidOid : MyDatabaseId);

  return (PgStat_StatIdxEntry *)

    pgstat_fetch_entry(PGSTAT_KIND_INDEX, dboid, reloid, may_free);

}