/*------------------------------------------------------------------------- * * pg_stat_statements.c * Track statement planning and execution times as well as resource * usage across a whole database cluster. * * Execution costs are totaled for each distinct source query, and kept in * a shared hashtable. (We track only as many distinct queries as will fit * in the designated amount of shared memory.) * * Starting in Postgres 9.2, this module normalized query entries. As of * Postgres 14, the normalization is done by the core if compute_query_id is * enabled, or optionally by third-party modules. * * To facilitate presenting entries to users, we create "representative" query * strings in which constants are replaced with parameter symbols ($n), to * make it clearer what a normalized entry can represent. To save on shared * memory, and to avoid having to truncate oversized query strings, we store * these strings in a temporary external query-texts file. Offsets into this * file are kept in shared memory. * * Note about locking issues: to create or delete an entry in the shared * hashtable, one must hold pgss->lock exclusively. Modifying any field * in an entry except the counters requires the same. To look up an entry, * one must hold the lock shared. To read or update the counters within * an entry, one must hold the lock shared or exclusive (so the entry doesn't * disappear!) and also take the entry's mutex spinlock. * The shared state variable pgss->extent (the next free spot in the external * query-text file) should be accessed only while holding either the * pgss->mutex spinlock, or exclusive lock on pgss->lock. We use the mutex to * allow reserving file space while holding only shared lock on pgss->lock. * Rewriting the entire external query-text file, eg for garbage collection, * requires holding pgss->lock exclusively; this allows individual entries * in the file to be read or written while holding only shared lock. * * * Copyright (c) 2008-2024, PostgreSQL Global Development Group * * IDENTIFICATION * contrib/pg_stat_statements/pg_stat_statements.c * *------------------------------------------------------------------------- */ #include "postgres.h" #include #include #include #include "access/parallel.h" #include "catalog/pg_authid.h" #include "common/hashfn.h" #include "common/int.h" #include "executor/instrument.h" #include "funcapi.h" #include "jit/jit.h" #include "mb/pg_wchar.h" #include "miscadmin.h" #include "nodes/queryjumble.h" #include "optimizer/planner.h" #include "parser/analyze.h" #include "parser/parsetree.h" #include "parser/scanner.h" #include "parser/scansup.h" #include "pgstat.h" #include "storage/fd.h" #include "storage/ipc.h" #include "storage/lwlock.h" #include "storage/shmem.h" #include "storage/spin.h" #include "tcop/utility.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/memutils.h" #include "utils/timestamp.h" PG_MODULE_MAGIC; /* Location of permanent stats file (valid when database is shut down) */ #define PGSS_DUMP_FILE PGSTAT_STAT_PERMANENT_DIRECTORY "/pg_stat_statements.stat" /* * Location of external query text file. */ #define PGSS_TEXT_FILE PG_STAT_TMP_DIR "/pgss_query_texts.stat" /* Magic number identifying the stats file format */ static const uint32 PGSS_FILE_HEADER = 0x20220408; /* PostgreSQL major version number, changes in which invalidate all entries */ static const uint32 PGSS_PG_MAJOR_VERSION = PG_VERSION_NUM / 100; /* XXX: Should USAGE_EXEC reflect execution time and/or buffer usage? */ #define USAGE_EXEC(duration) (1.0) #define USAGE_INIT (1.0) /* including initial planning */ #define ASSUMED_MEDIAN_INIT (10.0) /* initial assumed median usage */ #define ASSUMED_LENGTH_INIT 1024 /* initial assumed mean query length */ #define USAGE_DECREASE_FACTOR (0.99) /* decreased every entry_dealloc */ #define STICKY_DECREASE_FACTOR (0.50) /* factor for sticky entries */ #define USAGE_DEALLOC_PERCENT 5 /* free this % of entries at once */ #define IS_STICKY(c) ((c.calls[PGSS_PLAN] + c.calls[PGSS_EXEC]) == 0) /* * Extension version number, for supporting older extension versions' objects */ typedef enum pgssVersion { PGSS_V1_0 = 0, PGSS_V1_1, PGSS_V1_2, PGSS_V1_3, PGSS_V1_8, PGSS_V1_9, PGSS_V1_10, PGSS_V1_11, } pgssVersion; typedef enum pgssStoreKind { PGSS_INVALID = -1, /* * PGSS_PLAN and PGSS_EXEC must be respectively 0 and 1 as they're used to * reference the underlying values in the arrays in the Counters struct, * and this order is required in pg_stat_statements_internal(). */ PGSS_PLAN = 0, PGSS_EXEC, PGSS_NUMKIND /* Must be last value of this enum */ } pgssStoreKind; /* * Hashtable key that defines the identity of a hashtable entry. We separate * queries by user and by database even if they are otherwise identical. * * If you add a new key to this struct, make sure to teach pgss_store() to * zero the padding bytes. Otherwise, things will break, because pgss_hash is * created using HASH_BLOBS, and thus tag_hash is used to hash this. */ typedef struct pgssHashKey { Oid userid; /* user OID */ Oid dbid; /* database OID */ uint64 queryid; /* query identifier */ bool toplevel; /* query executed at top level */ } pgssHashKey; /* * The actual stats counters kept within pgssEntry. */ typedef struct Counters { int64 calls[PGSS_NUMKIND]; /* # of times planned/executed */ double total_time[PGSS_NUMKIND]; /* total planning/execution time, * in msec */ double min_time[PGSS_NUMKIND]; /* minimum planning/execution time in * msec since min/max reset */ double max_time[PGSS_NUMKIND]; /* maximum planning/execution time in * msec since min/max reset */ double mean_time[PGSS_NUMKIND]; /* mean planning/execution time in * msec */ double sum_var_time[PGSS_NUMKIND]; /* sum of variances in * planning/execution time in msec */ int64 rows; /* total # of retrieved or affected rows */ int64 shared_blks_hit; /* # of shared buffer hits */ int64 shared_blks_read; /* # of shared disk blocks read */ int64 shared_blks_dirtied; /* # of shared disk blocks dirtied */ int64 shared_blks_written; /* # of shared disk blocks written */ int64 local_blks_hit; /* # of local buffer hits */ int64 local_blks_read; /* # of local disk blocks read */ int64 local_blks_dirtied; /* # of local disk blocks dirtied */ int64 local_blks_written; /* # of local disk blocks written */ int64 temp_blks_read; /* # of temp blocks read */ int64 temp_blks_written; /* # of temp blocks written */ double shared_blk_read_time; /* time spent reading shared blocks, * in msec */ double shared_blk_write_time; /* time spent writing shared blocks, * in msec */ double local_blk_read_time; /* time spent reading local blocks, in * msec */ double local_blk_write_time; /* time spent writing local blocks, in * msec */ double temp_blk_read_time; /* time spent reading temp blocks, in msec */ double temp_blk_write_time; /* time spent writing temp blocks, in * msec */ double usage; /* usage factor */ int64 wal_records; /* # of WAL records generated */ int64 wal_fpi; /* # of WAL full page images generated */ uint64 wal_bytes; /* total amount of WAL generated in bytes */ int64 jit_functions; /* total number of JIT functions emitted */ double jit_generation_time; /* total time to generate jit code */ int64 jit_inlining_count; /* number of times inlining time has been * > 0 */ double jit_deform_time; /* total time to deform tuples in jit code */ int64 jit_deform_count; /* number of times deform time has been > * 0 */ double jit_inlining_time; /* total time to inline jit code */ int64 jit_optimization_count; /* number of times optimization time * has been > 0 */ double jit_optimization_time; /* total time to optimize jit code */ int64 jit_emission_count; /* number of times emission time has been * > 0 */ double jit_emission_time; /* total time to emit jit code */ } Counters; /* * Global statistics for pg_stat_statements */ typedef struct pgssGlobalStats { int64 dealloc; /* # of times entries were deallocated */ TimestampTz stats_reset; /* timestamp with all stats reset */ } pgssGlobalStats; /* * Statistics per statement * * Note: in event of a failure in garbage collection of the query text file, * we reset query_offset to zero and query_len to -1. This will be seen as * an invalid state by qtext_fetch(). */ typedef struct pgssEntry { pgssHashKey key; /* hash key of entry - MUST BE FIRST */ Counters counters; /* the statistics for this query */ Size query_offset; /* query text offset in external file */ int query_len; /* # of valid bytes in query string, or -1 */ int encoding; /* query text encoding */ TimestampTz stats_since; /* timestamp of entry allocation */ TimestampTz minmax_stats_since; /* timestamp of last min/max values reset */ slock_t mutex; /* protects the counters only */ } pgssEntry; /* * Global shared state */ typedef struct pgssSharedState { LWLock *lock; /* protects hashtable search/modification */ double cur_median_usage; /* current median usage in hashtable */ Size mean_query_len; /* current mean entry text length */ slock_t mutex; /* protects following fields only: */ Size extent; /* current extent of query file */ int n_writers; /* number of active writers to query file */ int gc_count; /* query file garbage collection cycle count */ pgssGlobalStats stats; /* global statistics for pgss */ } pgssSharedState; /*---- Local variables ----*/ /* Current nesting depth of planner/ExecutorRun/ProcessUtility calls */ static int nesting_level = 0; /* Saved hook values in case of unload */ static shmem_request_hook_type prev_shmem_request_hook = NULL; static shmem_startup_hook_type prev_shmem_startup_hook = NULL; static post_parse_analyze_hook_type prev_post_parse_analyze_hook = NULL; static planner_hook_type prev_planner_hook = NULL; static ExecutorStart_hook_type prev_ExecutorStart = NULL; static ExecutorRun_hook_type prev_ExecutorRun = NULL; static ExecutorFinish_hook_type prev_ExecutorFinish = NULL; static ExecutorEnd_hook_type prev_ExecutorEnd = NULL; static ProcessUtility_hook_type prev_ProcessUtility = NULL; /* Links to shared memory state */ static pgssSharedState *pgss = NULL; static HTAB *pgss_hash = NULL; /*---- GUC variables ----*/ typedef enum { PGSS_TRACK_NONE, /* track no statements */ PGSS_TRACK_TOP, /* only top level statements */ PGSS_TRACK_ALL, /* all statements, including nested ones */ } PGSSTrackLevel; static const struct config_enum_entry track_options[] = { {"none", PGSS_TRACK_NONE, false}, {"top", PGSS_TRACK_TOP, false}, {"all", PGSS_TRACK_ALL, false}, {NULL, 0, false} }; static int pgss_max = 5000; /* max # statements to track */ static int pgss_track = PGSS_TRACK_TOP; /* tracking level */ static bool pgss_track_utility = true; /* whether to track utility commands */ static bool pgss_track_planning = false; /* whether to track planning * duration */ static bool pgss_save = true; /* whether to save stats across shutdown */ #define pgss_enabled(level) \ (!IsParallelWorker() && \ (pgss_track == PGSS_TRACK_ALL || \ (pgss_track == PGSS_TRACK_TOP && (level) == 0))) #define record_gc_qtexts() \ do { \ volatile pgssSharedState *s = (volatile pgssSharedState *) pgss; \ SpinLockAcquire(&s->mutex); \ s->gc_count++; \ SpinLockRelease(&s->mutex); \ } while(0) /*---- Function declarations ----*/ PG_FUNCTION_INFO_V1(pg_stat_statements_reset); PG_FUNCTION_INFO_V1(pg_stat_statements_reset_1_7); PG_FUNCTION_INFO_V1(pg_stat_statements_reset_1_11); PG_FUNCTION_INFO_V1(pg_stat_statements_1_2); PG_FUNCTION_INFO_V1(pg_stat_statements_1_3); PG_FUNCTION_INFO_V1(pg_stat_statements_1_8); PG_FUNCTION_INFO_V1(pg_stat_statements_1_9); PG_FUNCTION_INFO_V1(pg_stat_statements_1_10); PG_FUNCTION_INFO_V1(pg_stat_statements_1_11); PG_FUNCTION_INFO_V1(pg_stat_statements); PG_FUNCTION_INFO_V1(pg_stat_statements_info); static void pgss_shmem_request(void); static void pgss_shmem_startup(void); static void pgss_shmem_shutdown(int code, Datum arg); static void pgss_post_parse_analyze(ParseState *pstate, Query *query, JumbleState *jstate); static PlannedStmt *pgss_planner(Query *parse, const char *query_string, int cursorOptions, ParamListInfo boundParams); static void pgss_ExecutorStart(QueryDesc *queryDesc, int eflags); static void pgss_ExecutorRun(QueryDesc *queryDesc, ScanDirection direction, uint64 count, bool execute_once); static void pgss_ExecutorFinish(QueryDesc *queryDesc); static void pgss_ExecutorEnd(QueryDesc *queryDesc); static void pgss_ProcessUtility(PlannedStmt *pstmt, const char *queryString, bool readOnlyTree, ProcessUtilityContext context, ParamListInfo params, QueryEnvironment *queryEnv, DestReceiver *dest, QueryCompletion *qc); static void pgss_store(const char *query, uint64 queryId, int query_location, int query_len, pgssStoreKind kind, double total_time, uint64 rows, const BufferUsage *bufusage, const WalUsage *walusage, const struct JitInstrumentation *jitusage, JumbleState *jstate); static void pg_stat_statements_internal(FunctionCallInfo fcinfo, pgssVersion api_version, bool showtext); static Size pgss_memsize(void); static pgssEntry *entry_alloc(pgssHashKey *key, Size query_offset, int query_len, int encoding, bool sticky); static void entry_dealloc(void); static bool qtext_store(const char *query, int query_len, Size *query_offset, int *gc_count); static char *qtext_load_file(Size *buffer_size); static char *qtext_fetch(Size query_offset, int query_len, char *buffer, Size buffer_size); static bool need_gc_qtexts(void); static void gc_qtexts(void); static TimestampTz entry_reset(Oid userid, Oid dbid, uint64 queryid, bool minmax_only); static char *generate_normalized_query(JumbleState *jstate, const char *query, int query_loc, int *query_len_p); static void fill_in_constant_lengths(JumbleState *jstate, const char *query, int query_loc); static int comp_location(const void *a, const void *b); /* * Module load callback */ void _PG_init(void) { /* * In order to create our shared memory area, we have to be loaded via * shared_preload_libraries. If not, fall out without hooking into any of * the main system. (We don't throw error here because it seems useful to * allow the pg_stat_statements functions to be created even when the * module isn't active. The functions must protect themselves against * being called then, however.) */ if (!process_shared_preload_libraries_in_progress) return; /* * Inform the postmaster that we want to enable query_id calculation if * compute_query_id is set to auto. */ EnableQueryId(); /* * Define (or redefine) custom GUC variables. */ DefineCustomIntVariable("pg_stat_statements.max", "Sets the maximum number of statements tracked by pg_stat_statements.", NULL, &pgss_max, 5000, 100, INT_MAX / 2, PGC_POSTMASTER, 0, NULL, NULL, NULL); DefineCustomEnumVariable("pg_stat_statements.track", "Selects which statements are tracked by pg_stat_statements.", NULL, &pgss_track, PGSS_TRACK_TOP, track_options, PGC_SUSET, 0, NULL, NULL, NULL); DefineCustomBoolVariable("pg_stat_statements.track_utility", "Selects whether utility commands are tracked by pg_stat_statements.", NULL, &pgss_track_utility, true, PGC_SUSET, 0, NULL, NULL, NULL); DefineCustomBoolVariable("pg_stat_statements.track_planning", "Selects whether planning duration is tracked by pg_stat_statements.", NULL, &pgss_track_planning, false, PGC_SUSET, 0, NULL, NULL, NULL); DefineCustomBoolVariable("pg_stat_statements.save", "Save pg_stat_statements statistics across server shutdowns.", NULL, &pgss_save, true, PGC_SIGHUP, 0, NULL, NULL, NULL); MarkGUCPrefixReserved("pg_stat_statements"); /* * Install hooks. */ prev_shmem_request_hook = shmem_request_hook; shmem_request_hook = pgss_shmem_request; prev_shmem_startup_hook = shmem_startup_hook; shmem_startup_hook = pgss_shmem_startup; prev_post_parse_analyze_hook = post_parse_analyze_hook; post_parse_analyze_hook = pgss_post_parse_analyze; prev_planner_hook = planner_hook; planner_hook = pgss_planner; prev_ExecutorStart = ExecutorStart_hook; ExecutorStart_hook = pgss_ExecutorStart; prev_ExecutorRun = ExecutorRun_hook; ExecutorRun_hook = pgss_ExecutorRun; prev_ExecutorFinish = ExecutorFinish_hook; ExecutorFinish_hook = pgss_ExecutorFinish; prev_ExecutorEnd = ExecutorEnd_hook; ExecutorEnd_hook = pgss_ExecutorEnd; prev_ProcessUtility = ProcessUtility_hook; ProcessUtility_hook = pgss_ProcessUtility; } /* * shmem_request hook: request additional shared resources. We'll allocate or * attach to the shared resources in pgss_shmem_startup(). */ static void pgss_shmem_request(void) { if (prev_shmem_request_hook) prev_shmem_request_hook(); RequestAddinShmemSpace(pgss_memsize()); RequestNamedLWLockTranche("pg_stat_statements", 1); } /* * shmem_startup hook: allocate or attach to shared memory, * then load any pre-existing statistics from file. * Also create and load the query-texts file, which is expected to exist * (even if empty) while the module is enabled. */ static void pgss_shmem_startup(void) { bool found; HASHCTL info; FILE *file = NULL; FILE *qfile = NULL; uint32 header; int32 num; int32 pgver; int32 i; int buffer_size; char *buffer = NULL; if (prev_shmem_startup_hook) prev_shmem_startup_hook(); /* reset in case this is a restart within the postmaster */ pgss = NULL; pgss_hash = NULL; /* * Create or attach to the shared memory state, including hash table */ LWLockAcquire(AddinShmemInitLock, LW_EXCLUSIVE); pgss = ShmemInitStruct("pg_stat_statements", sizeof(pgssSharedState), &found); if (!found) { /* First time through ... */ pgss->lock = &(GetNamedLWLockTranche("pg_stat_statements"))->lock; pgss->cur_median_usage = ASSUMED_MEDIAN_INIT; pgss->mean_query_len = ASSUMED_LENGTH_INIT; SpinLockInit(&pgss->mutex); pgss->extent = 0; pgss->n_writers = 0; pgss->gc_count = 0; pgss->stats.dealloc = 0; pgss->stats.stats_reset = GetCurrentTimestamp(); } info.keysize = sizeof(pgssHashKey); info.entrysize = sizeof(pgssEntry); pgss_hash = ShmemInitHash("pg_stat_statements hash", pgss_max, pgss_max, &info, HASH_ELEM | HASH_BLOBS); LWLockRelease(AddinShmemInitLock); /* * If we're in the postmaster (or a standalone backend...), set up a shmem * exit hook to dump the statistics to disk. */ if (!IsUnderPostmaster) on_shmem_exit(pgss_shmem_shutdown, (Datum) 0); /* * Done if some other process already completed our initialization. */ if (found) return; /* * Note: we don't bother with locks here, because there should be no other * processes running when this code is reached. */ /* Unlink query text file possibly left over from crash */ unlink(PGSS_TEXT_FILE); /* Allocate new query text temp file */ qfile = AllocateFile(PGSS_TEXT_FILE, PG_BINARY_W); if (qfile == NULL) goto write_error; /* * If we were told not to load old statistics, we're done. (Note we do * not try to unlink any old dump file in this case. This seems a bit * questionable but it's the historical behavior.) */ if (!pgss_save) { FreeFile(qfile); return; } /* * Attempt to load old statistics from the dump file. */ file = AllocateFile(PGSS_DUMP_FILE, PG_BINARY_R); if (file == NULL) { if (errno != ENOENT) goto read_error; /* No existing persisted stats file, so we're done */ FreeFile(qfile); return; } buffer_size = 2048; buffer = (char *) palloc(buffer_size); if (fread(&header, sizeof(uint32), 1, file) != 1 || fread(&pgver, sizeof(uint32), 1, file) != 1 || fread(&num, sizeof(int32), 1, file) != 1) goto read_error; if (header != PGSS_FILE_HEADER || pgver != PGSS_PG_MAJOR_VERSION) goto data_error; for (i = 0; i < num; i++) { pgssEntry temp; pgssEntry *entry; Size query_offset; if (fread(&temp, sizeof(pgssEntry), 1, file) != 1) goto read_error; /* Encoding is the only field we can easily sanity-check */ if (!PG_VALID_BE_ENCODING(temp.encoding)) goto data_error; /* Resize buffer as needed */ if (temp.query_len >= buffer_size) { buffer_size = Max(buffer_size * 2, temp.query_len + 1); buffer = repalloc(buffer, buffer_size); } if (fread(buffer, 1, temp.query_len + 1, file) != temp.query_len + 1) goto read_error; /* Should have a trailing null, but let's make sure */ buffer[temp.query_len] = '\0'; /* Skip loading "sticky" entries */ if (IS_STICKY(temp.counters)) continue; /* Store the query text */ query_offset = pgss->extent; if (fwrite(buffer, 1, temp.query_len + 1, qfile) != temp.query_len + 1) goto write_error; pgss->extent += temp.query_len + 1; /* make the hashtable entry (discards old entries if too many) */ entry = entry_alloc(&temp.key, query_offset, temp.query_len, temp.encoding, false); /* copy in the actual stats */ entry->counters = temp.counters; entry->stats_since = temp.stats_since; entry->minmax_stats_since = temp.minmax_stats_since; } /* Read global statistics for pg_stat_statements */ if (fread(&pgss->stats, sizeof(pgssGlobalStats), 1, file) != 1) goto read_error; pfree(buffer); FreeFile(file); FreeFile(qfile); /* * Remove the persisted stats file so it's not included in * backups/replication standbys, etc. A new file will be written on next * shutdown. * * Note: it's okay if the PGSS_TEXT_FILE is included in a basebackup, * because we remove that file on startup; it acts inversely to * PGSS_DUMP_FILE, in that it is only supposed to be around when the * server is running, whereas PGSS_DUMP_FILE is only supposed to be around * when the server is not running. Leaving the file creates no danger of * a newly restored database having a spurious record of execution costs, * which is what we're really concerned about here. */ unlink(PGSS_DUMP_FILE); return; read_error: ereport(LOG, (errcode_for_file_access(), errmsg("could not read file \"%s\": %m", PGSS_DUMP_FILE))); goto fail; data_error: ereport(LOG, (errcode(ERRCODE_INVALID_PARAMETER_VALUE), errmsg("ignoring invalid data in file \"%s\"", PGSS_DUMP_FILE))); goto fail; write_error: ereport(LOG, (errcode_for_file_access(), errmsg("could not write file \"%s\": %m", PGSS_TEXT_FILE))); fail: if (buffer) pfree(buffer); if (file) FreeFile(file); if (qfile) FreeFile(qfile); /* If possible, throw away the bogus file; ignore any error */ unlink(PGSS_DUMP_FILE); /* * Don't unlink PGSS_TEXT_FILE here; it should always be around while the * server is running with pg_stat_statements enabled */ } /* * shmem_shutdown hook: Dump statistics into file. * * Note: we don't bother with acquiring lock, because there should be no * other processes running when this is called. */ static void pgss_shmem_shutdown(int code, Datum arg) { FILE *file; char *qbuffer = NULL; Size qbuffer_size = 0; HASH_SEQ_STATUS hash_seq; int32 num_entries; pgssEntry *entry; /* Don't try to dump during a crash. */ if (code) return; /* Safety check ... shouldn't get here unless shmem is set up. */ if (!pgss || !pgss_hash) return; /* Don't dump if told not to. */ if (!pgss_save) return; file = AllocateFile(PGSS_DUMP_FILE ".tmp", PG_BINARY_W); if (file == NULL) goto error; if (fwrite(&PGSS_FILE_HEADER, sizeof(uint32), 1, file) != 1) goto error; if (fwrite(&PGSS_PG_MAJOR_VERSION, sizeof(uint32), 1, file) != 1) goto error; num_entries = hash_get_num_entries(pgss_hash); if (fwrite(&num_entries, sizeof(int32), 1, file) != 1) goto error; qbuffer = qtext_load_file(&qbuffer_size); if (qbuffer == NULL) goto error; /* * When serializing to disk, we store query texts immediately after their * entry data. Any orphaned query texts are thereby excluded. */ hash_seq_init(&hash_seq, pgss_hash); while ((entry = hash_seq_search(&hash_seq)) != NULL) { int len = entry->query_len; char *qstr = qtext_fetch(entry->query_offset, len, qbuffer, qbuffer_size); if (qstr == NULL) continue; /* Ignore any entries with bogus texts */ if (fwrite(entry, sizeof(pgssEntry), 1, file) != 1 || fwrite(qstr, 1, len + 1, file) != len + 1) { /* note: we assume hash_seq_term won't change errno */ hash_seq_term(&hash_seq); goto error; } } /* Dump global statistics for pg_stat_statements */ if (fwrite(&pgss->stats, sizeof(pgssGlobalStats), 1, file) != 1) goto error; free(qbuffer); qbuffer = NULL; if (FreeFile(file)) { file = NULL; goto error; } /* * Rename file into place, so we atomically replace any old one. */ (void) durable_rename(PGSS_DUMP_FILE ".tmp", PGSS_DUMP_FILE, LOG); /* Unlink query-texts file; it's not needed while shutdown */ unlink(PGSS_TEXT_FILE); return; error: ereport(LOG, (errcode_for_file_access(), errmsg("could not write file \"%s\": %m", PGSS_DUMP_FILE ".tmp"))); free(qbuffer); if (file) FreeFile(file); unlink(PGSS_DUMP_FILE ".tmp"); unlink(PGSS_TEXT_FILE); } /* * Post-parse-analysis hook: mark query with a queryId */ static void pgss_post_parse_analyze(ParseState *pstate, Query *query, JumbleState *jstate) { if (prev_post_parse_analyze_hook) prev_post_parse_analyze_hook(pstate, query, jstate); /* Safety check... */ if (!pgss || !pgss_hash || !pgss_enabled(nesting_level)) return; /* * If it's EXECUTE, clear the queryId so that stats will accumulate for * the underlying PREPARE. But don't do this if we're not tracking * utility statements, to avoid messing up another extension that might be * tracking them. */ if (query->utilityStmt) { if (pgss_track_utility && IsA(query->utilityStmt, ExecuteStmt)) { query->queryId = UINT64CONST(0); return; } } /* * If query jumbling were able to identify any ignorable constants, we * immediately create a hash table entry for the query, so that we can * record the normalized form of the query string. If there were no such * constants, the normalized string would be the same as the query text * anyway, so there's no need for an early entry. */ if (jstate && jstate->clocations_count > 0) pgss_store(pstate->p_sourcetext, query->queryId, query->stmt_location, query->stmt_len, PGSS_INVALID, 0, 0, NULL, NULL, NULL, jstate); } /* * Planner hook: forward to regular planner, but measure planning time * if needed. */ static PlannedStmt * pgss_planner(Query *parse, const char *query_string, int cursorOptions, ParamListInfo boundParams) { PlannedStmt *result; /* * We can't process the query if no query_string is provided, as * pgss_store needs it. We also ignore query without queryid, as it would * be treated as a utility statement, which may not be the case. * * Note that planner_hook can be called from the planner itself, so we * have a specific nesting level for the planner. However, utility * commands containing optimizable statements can also call the planner, * same for regular DML (for instance for underlying foreign key queries). * So testing the planner nesting level only is not enough to detect real * top level planner call. */ if (pgss_enabled(nesting_level) && pgss_track_planning && query_string && parse->queryId != UINT64CONST(0)) { instr_time start; instr_time duration; BufferUsage bufusage_start, bufusage; WalUsage walusage_start, walusage; /* We need to track buffer usage as the planner can access them. */ bufusage_start = pgBufferUsage; /* * Similarly the planner could write some WAL records in some cases * (e.g. setting a hint bit with those being WAL-logged) */ walusage_start = pgWalUsage; INSTR_TIME_SET_CURRENT(start); nesting_level++; PG_TRY(); { if (prev_planner_hook) result = prev_planner_hook(parse, query_string, cursorOptions, boundParams); else result = standard_planner(parse, query_string, cursorOptions, boundParams); } PG_FINALLY(); { nesting_level--; } PG_END_TRY(); INSTR_TIME_SET_CURRENT(duration); INSTR_TIME_SUBTRACT(duration, start); /* calc differences of buffer counters. */ memset(&bufusage, 0, sizeof(BufferUsage)); BufferUsageAccumDiff(&bufusage, &pgBufferUsage, &bufusage_start); /* calc differences of WAL counters. */ memset(&walusage, 0, sizeof(WalUsage)); WalUsageAccumDiff(&walusage, &pgWalUsage, &walusage_start); pgss_store(query_string, parse->queryId, parse->stmt_location, parse->stmt_len, PGSS_PLAN, INSTR_TIME_GET_MILLISEC(duration), 0, &bufusage, &walusage, NULL, NULL); } else { /* * Even though we're not tracking plan time for this statement, we * must still increment the nesting level, to ensure that functions * evaluated during planning are not seen as top-level calls. */ nesting_level++; PG_TRY(); { if (prev_planner_hook) result = prev_planner_hook(parse, query_string, cursorOptions, boundParams); else result = standard_planner(parse, query_string, cursorOptions, boundParams); } PG_FINALLY(); { nesting_level--; } PG_END_TRY(); } return result; } /* * ExecutorStart hook: start up tracking if needed */ static void pgss_ExecutorStart(QueryDesc *queryDesc, int eflags) { if (prev_ExecutorStart) prev_ExecutorStart(queryDesc, eflags); else standard_ExecutorStart(queryDesc, eflags); /* * If query has queryId zero, don't track it. This prevents double * counting of optimizable statements that are directly contained in * utility statements. */ if (pgss_enabled(nesting_level) && queryDesc->plannedstmt->queryId != UINT64CONST(0)) { /* * Set up to track total elapsed time in ExecutorRun. Make sure the * space is allocated in the per-query context so it will go away at * ExecutorEnd. */ if (queryDesc->totaltime == NULL) { MemoryContext oldcxt; oldcxt = MemoryContextSwitchTo(queryDesc->estate->es_query_cxt); queryDesc->totaltime = InstrAlloc(1, INSTRUMENT_ALL, false); MemoryContextSwitchTo(oldcxt); } } } /* * ExecutorRun hook: all we need do is track nesting depth */ static void pgss_ExecutorRun(QueryDesc *queryDesc, ScanDirection direction, uint64 count, bool execute_once) { nesting_level++; PG_TRY(); { if (prev_ExecutorRun) prev_ExecutorRun(queryDesc, direction, count, execute_once); else standard_ExecutorRun(queryDesc, direction, count, execute_once); } PG_FINALLY(); { nesting_level--; } PG_END_TRY(); } /* * ExecutorFinish hook: all we need do is track nesting depth */ static void pgss_ExecutorFinish(QueryDesc *queryDesc) { nesting_level++; PG_TRY(); { if (prev_ExecutorFinish) prev_ExecutorFinish(queryDesc); else standard_ExecutorFinish(queryDesc); } PG_FINALLY(); { nesting_level--; } PG_END_TRY(); } /* * ExecutorEnd hook: store results if needed */ static void pgss_ExecutorEnd(QueryDesc *queryDesc) { uint64 queryId = queryDesc->plannedstmt->queryId; if (queryId != UINT64CONST(0) && queryDesc->totaltime && pgss_enabled(nesting_level)) { /* * Make sure stats accumulation is done. (Note: it's okay if several * levels of hook all do this.) */ InstrEndLoop(queryDesc->totaltime); pgss_store(queryDesc->sourceText, queryId, queryDesc->plannedstmt->stmt_location, queryDesc->plannedstmt->stmt_len, PGSS_EXEC, queryDesc->totaltime->total * 1000.0, /* convert to msec */ queryDesc->estate->es_total_processed, &queryDesc->totaltime->bufusage, &queryDesc->totaltime->walusage, queryDesc->estate->es_jit ? &queryDesc->estate->es_jit->instr : NULL, NULL); } if (prev_ExecutorEnd) prev_ExecutorEnd(queryDesc); else standard_ExecutorEnd(queryDesc); } /* * ProcessUtility hook */ static void pgss_ProcessUtility(PlannedStmt *pstmt, const char *queryString, bool readOnlyTree, ProcessUtilityContext context, ParamListInfo params, QueryEnvironment *queryEnv, DestReceiver *dest, QueryCompletion *qc) { Node *parsetree = pstmt->utilityStmt; uint64 saved_queryId = pstmt->queryId; int saved_stmt_location = pstmt->stmt_location; int saved_stmt_len = pstmt->stmt_len; bool enabled = pgss_track_utility && pgss_enabled(nesting_level); /* * Force utility statements to get queryId zero. We do this even in cases * where the statement contains an optimizable statement for which a * queryId could be derived (such as EXPLAIN or DECLARE CURSOR). For such * cases, runtime control will first go through ProcessUtility and then * the executor, and we don't want the executor hooks to do anything, * since we are already measuring the statement's costs at the utility * level. * * Note that this is only done if pg_stat_statements is enabled and * configured to track utility statements, in the unlikely possibility * that user configured another extension to handle utility statements * only. */ if (enabled) pstmt->queryId = UINT64CONST(0); /* * If it's an EXECUTE statement, we don't track it and don't increment the * nesting level. This allows the cycles to be charged to the underlying * PREPARE instead (by the Executor hooks), which is much more useful. * * We also don't track execution of PREPARE. If we did, we would get one * hash table entry for the PREPARE (with hash calculated from the query * string), and then a different one with the same query string (but hash * calculated from the query tree) would be used to accumulate costs of * ensuing EXECUTEs. This would be confusing. Since PREPARE doesn't * actually run the planner (only parse+rewrite), its costs are generally * pretty negligible and it seems okay to just ignore it. */ if (enabled && !IsA(parsetree, ExecuteStmt) && !IsA(parsetree, PrepareStmt)) { instr_time start; instr_time duration; uint64 rows; BufferUsage bufusage_start, bufusage; WalUsage walusage_start, walusage; bufusage_start = pgBufferUsage; walusage_start = pgWalUsage; INSTR_TIME_SET_CURRENT(start); nesting_level++; PG_TRY(); { if (prev_ProcessUtility) prev_ProcessUtility(pstmt, queryString, readOnlyTree, context, params, queryEnv, dest, qc); else standard_ProcessUtility(pstmt, queryString, readOnlyTree, context, params, queryEnv, dest, qc); } PG_FINALLY(); { nesting_level--; } PG_END_TRY(); /* * CAUTION: do not access the *pstmt data structure again below here. * If it was a ROLLBACK or similar, that data structure may have been * freed. We must copy everything we still need into local variables, * which we did above. * * For the same reason, we can't risk restoring pstmt->queryId to its * former value, which'd otherwise be a good idea. */ INSTR_TIME_SET_CURRENT(duration); INSTR_TIME_SUBTRACT(duration, start); /* * Track the total number of rows retrieved or affected by the utility * statements of COPY, FETCH, CREATE TABLE AS, CREATE MATERIALIZED * VIEW, REFRESH MATERIALIZED VIEW and SELECT INTO. */ rows = (qc && (qc->commandTag == CMDTAG_COPY || qc->commandTag == CMDTAG_FETCH || qc->commandTag == CMDTAG_SELECT || qc->commandTag == CMDTAG_REFRESH_MATERIALIZED_VIEW)) ? qc->nprocessed : 0; /* calc differences of buffer counters. */ memset(&bufusage, 0, sizeof(BufferUsage)); BufferUsageAccumDiff(&bufusage, &pgBufferUsage, &bufusage_start); /* calc differences of WAL counters. */ memset(&walusage, 0, sizeof(WalUsage)); WalUsageAccumDiff(&walusage, &pgWalUsage, &walusage_start); pgss_store(queryString, saved_queryId, saved_stmt_location, saved_stmt_len, PGSS_EXEC, INSTR_TIME_GET_MILLISEC(duration), rows, &bufusage, &walusage, NULL, NULL); } else { /* * Even though we're not tracking execution time for this statement, * we must still increment the nesting level, to ensure that functions * evaluated within it are not seen as top-level calls. But don't do * so for EXECUTE; that way, when control reaches pgss_planner or * pgss_ExecutorStart, we will treat the costs as top-level if * appropriate. Likewise, don't bump for PREPARE, so that parse * analysis will treat the statement as top-level if appropriate. * * To be absolutely certain we don't mess up the nesting level, * evaluate the bump_level condition just once. */ bool bump_level = !IsA(parsetree, ExecuteStmt) && !IsA(parsetree, PrepareStmt); if (bump_level) nesting_level++; PG_TRY(); { if (prev_ProcessUtility) prev_ProcessUtility(pstmt, queryString, readOnlyTree, context, params, queryEnv, dest, qc); else standard_ProcessUtility(pstmt, queryString, readOnlyTree, context, params, queryEnv, dest, qc); } PG_FINALLY(); { if (bump_level) nesting_level--; } PG_END_TRY(); } } /* * Store some statistics for a statement. * * If jstate is not NULL then we're trying to create an entry for which * we have no statistics as yet; we just want to record the normalized * query string. total_time, rows, bufusage and walusage are ignored in this * case. * * If kind is PGSS_PLAN or PGSS_EXEC, its value is used as the array position * for the arrays in the Counters field. */ static void pgss_store(const char *query, uint64 queryId, int query_location, int query_len, pgssStoreKind kind, double total_time, uint64 rows, const BufferUsage *bufusage, const WalUsage *walusage, const struct JitInstrumentation *jitusage, JumbleState *jstate) { pgssHashKey key; pgssEntry *entry; char *norm_query = NULL; int encoding = GetDatabaseEncoding(); Assert(query != NULL); /* Safety check... */ if (!pgss || !pgss_hash) return; /* * Nothing to do if compute_query_id isn't enabled and no other module * computed a query identifier. */ if (queryId == UINT64CONST(0)) return; /* * Confine our attention to the relevant part of the string, if the query * is a portion of a multi-statement source string, and update query * location and length if needed. */ query = CleanQuerytext(query, &query_location, &query_len); /* Set up key for hashtable search */ /* clear padding */ memset(&key, 0, sizeof(pgssHashKey)); key.userid = GetUserId(); key.dbid = MyDatabaseId; key.queryid = queryId; key.toplevel = (nesting_level == 0); /* Lookup the hash table entry with shared lock. */ LWLockAcquire(pgss->lock, LW_SHARED); entry = (pgssEntry *) hash_search(pgss_hash, &key, HASH_FIND, NULL); /* Create new entry, if not present */ if (!entry) { Size query_offset; int gc_count; bool stored; bool do_gc; /* * Create a new, normalized query string if caller asked. We don't * need to hold the lock while doing this work. (Note: in any case, * it's possible that someone else creates a duplicate hashtable entry * in the interval where we don't hold the lock below. That case is * handled by entry_alloc.) */ if (jstate) { LWLockRelease(pgss->lock); norm_query = generate_normalized_query(jstate, query, query_location, &query_len); LWLockAcquire(pgss->lock, LW_SHARED); } /* Append new query text to file with only shared lock held */ stored = qtext_store(norm_query ? norm_query : query, query_len, &query_offset, &gc_count); /* * Determine whether we need to garbage collect external query texts * while the shared lock is still held. This micro-optimization * avoids taking the time to decide this while holding exclusive lock. */ do_gc = need_gc_qtexts(); /* Need exclusive lock to make a new hashtable entry - promote */ LWLockRelease(pgss->lock); LWLockAcquire(pgss->lock, LW_EXCLUSIVE); /* * A garbage collection may have occurred while we weren't holding the * lock. In the unlikely event that this happens, the query text we * stored above will have been garbage collected, so write it again. * This should be infrequent enough that doing it while holding * exclusive lock isn't a performance problem. */ if (!stored || pgss->gc_count != gc_count) stored = qtext_store(norm_query ? norm_query : query, query_len, &query_offset, NULL); /* If we failed to write to the text file, give up */ if (!stored) goto done; /* OK to create a new hashtable entry */ entry = entry_alloc(&key, query_offset, query_len, encoding, jstate != NULL); /* If needed, perform garbage collection while exclusive lock held */ if (do_gc) gc_qtexts(); } /* Increment the counts, except when jstate is not NULL */ if (!jstate) { /* * Grab the spinlock while updating the counters (see comment about * locking rules at the head of the file) */ volatile pgssEntry *e = (volatile pgssEntry *) entry; Assert(kind == PGSS_PLAN || kind == PGSS_EXEC); SpinLockAcquire(&e->mutex); /* "Unstick" entry if it was previously sticky */ if (IS_STICKY(e->counters)) e->counters.usage = USAGE_INIT; e->counters.calls[kind] += 1; e->counters.total_time[kind] += total_time; if (e->counters.calls[kind] == 1) { e->counters.min_time[kind] = total_time; e->counters.max_time[kind] = total_time; e->counters.mean_time[kind] = total_time; } else { /* * Welford's method for accurately computing variance. See * */ double old_mean = e->counters.mean_time[kind]; e->counters.mean_time[kind] += (total_time - old_mean) / e->counters.calls[kind]; e->counters.sum_var_time[kind] += (total_time - old_mean) * (total_time - e->counters.mean_time[kind]); /* * Calculate min and max time. min = 0 and max = 0 means that the * min/max statistics were reset */ if (e->counters.min_time[kind] == 0 && e->counters.max_time[kind] == 0) { e->counters.min_time[kind] = total_time; e->counters.max_time[kind] = total_time; } else { if (e->counters.min_time[kind] > total_time) e->counters.min_time[kind] = total_time; if (e->counters.max_time[kind] < total_time) e->counters.max_time[kind] = total_time; } } e->counters.rows += rows; e->counters.shared_blks_hit += bufusage->shared_blks_hit; e->counters.shared_blks_read += bufusage->shared_blks_read; e->counters.shared_blks_dirtied += bufusage->shared_blks_dirtied; e->counters.shared_blks_written += bufusage->shared_blks_written; e->counters.local_blks_hit += bufusage->local_blks_hit; e->counters.local_blks_read += bufusage->local_blks_read; e->counters.local_blks_dirtied += bufusage->local_blks_dirtied; e->counters.local_blks_written += bufusage->local_blks_written; e->counters.temp_blks_read += bufusage->temp_blks_read; e->counters.temp_blks_written += bufusage->temp_blks_written; e->counters.shared_blk_read_time += INSTR_TIME_GET_MILLISEC(bufusage->shared_blk_read_time); e->counters.shared_blk_write_time += INSTR_TIME_GET_MILLISEC(bufusage->shared_blk_write_time); e->counters.local_blk_read_time += INSTR_TIME_GET_MILLISEC(bufusage->local_blk_read_time); e->counters.local_blk_write_time += INSTR_TIME_GET_MILLISEC(bufusage->local_blk_write_time); e->counters.temp_blk_read_time += INSTR_TIME_GET_MILLISEC(bufusage->temp_blk_read_time); e->counters.temp_blk_write_time += INSTR_TIME_GET_MILLISEC(bufusage->temp_blk_write_time); e->counters.usage += USAGE_EXEC(total_time); e->counters.wal_records += walusage->wal_records; e->counters.wal_fpi += walusage->wal_fpi; e->counters.wal_bytes += walusage->wal_bytes; if (jitusage) { e->counters.jit_functions += jitusage->created_functions; e->counters.jit_generation_time += INSTR_TIME_GET_MILLISEC(jitusage->generation_counter); if (INSTR_TIME_GET_MILLISEC(jitusage->deform_counter)) e->counters.jit_deform_count++; e->counters.jit_deform_time += INSTR_TIME_GET_MILLISEC(jitusage->deform_counter); if (INSTR_TIME_GET_MILLISEC(jitusage->inlining_counter)) e->counters.jit_inlining_count++; e->counters.jit_inlining_time += INSTR_TIME_GET_MILLISEC(jitusage->inlining_counter); if (INSTR_TIME_GET_MILLISEC(jitusage->optimization_counter)) e->counters.jit_optimization_count++; e->counters.jit_optimization_time += INSTR_TIME_GET_MILLISEC(jitusage->optimization_counter); if (INSTR_TIME_GET_MILLISEC(jitusage->emission_counter)) e->counters.jit_emission_count++; e->counters.jit_emission_time += INSTR_TIME_GET_MILLISEC(jitusage->emission_counter); } SpinLockRelease(&e->mutex); } done: LWLockRelease(pgss->lock); /* We postpone this clean-up until we're out of the lock */ if (norm_query) pfree(norm_query); } /* * Reset statement statistics corresponding to userid, dbid, and queryid. */ Datum pg_stat_statements_reset_1_7(PG_FUNCTION_ARGS) { Oid userid; Oid dbid; uint64 queryid; userid = PG_GETARG_OID(0); dbid = PG_GETARG_OID(1); queryid = (uint64) PG_GETARG_INT64(2); entry_reset(userid, dbid, queryid, false); PG_RETURN_VOID(); } Datum pg_stat_statements_reset_1_11(PG_FUNCTION_ARGS) { Oid userid; Oid dbid; uint64 queryid; bool minmax_only; userid = PG_GETARG_OID(0); dbid = PG_GETARG_OID(1); queryid = (uint64) PG_GETARG_INT64(2); minmax_only = PG_GETARG_BOOL(3); PG_RETURN_TIMESTAMPTZ(entry_reset(userid, dbid, queryid, minmax_only)); } /* * Reset statement statistics. */ Datum pg_stat_statements_reset(PG_FUNCTION_ARGS) { entry_reset(0, 0, 0, false); PG_RETURN_VOID(); } /* Number of output arguments (columns) for various API versions */ #define PG_STAT_STATEMENTS_COLS_V1_0 14 #define PG_STAT_STATEMENTS_COLS_V1_1 18 #define PG_STAT_STATEMENTS_COLS_V1_2 19 #define PG_STAT_STATEMENTS_COLS_V1_3 23 #define PG_STAT_STATEMENTS_COLS_V1_8 32 #define PG_STAT_STATEMENTS_COLS_V1_9 33 #define PG_STAT_STATEMENTS_COLS_V1_10 43 #define PG_STAT_STATEMENTS_COLS_V1_11 49 #define PG_STAT_STATEMENTS_COLS 49 /* maximum of above */ /* * Retrieve statement statistics. * * The SQL API of this function has changed multiple times, and will likely * do so again in future. To support the case where a newer version of this * loadable module is being used with an old SQL declaration of the function, * we continue to support the older API versions. For 1.2 and later, the * expected API version is identified by embedding it in the C name of the * function. Unfortunately we weren't bright enough to do that for 1.1. */ Datum pg_stat_statements_1_11(PG_FUNCTION_ARGS) { bool showtext = PG_GETARG_BOOL(0); pg_stat_statements_internal(fcinfo, PGSS_V1_11, showtext); return (Datum) 0; } Datum pg_stat_statements_1_10(PG_FUNCTION_ARGS) { bool showtext = PG_GETARG_BOOL(0); pg_stat_statements_internal(fcinfo, PGSS_V1_10, showtext); return (Datum) 0; } Datum pg_stat_statements_1_9(PG_FUNCTION_ARGS) { bool showtext = PG_GETARG_BOOL(0); pg_stat_statements_internal(fcinfo, PGSS_V1_9, showtext); return (Datum) 0; } Datum pg_stat_statements_1_8(PG_FUNCTION_ARGS) { bool showtext = PG_GETARG_BOOL(0); pg_stat_statements_internal(fcinfo, PGSS_V1_8, showtext); return (Datum) 0; } Datum pg_stat_statements_1_3(PG_FUNCTION_ARGS) { bool showtext = PG_GETARG_BOOL(0); pg_stat_statements_internal(fcinfo, PGSS_V1_3, showtext); return (Datum) 0; } Datum pg_stat_statements_1_2(PG_FUNCTION_ARGS) { bool showtext = PG_GETARG_BOOL(0); pg_stat_statements_internal(fcinfo, PGSS_V1_2, showtext); return (Datum) 0; } /* * Legacy entry point for pg_stat_statements() API versions 1.0 and 1.1. * This can be removed someday, perhaps. */ Datum pg_stat_statements(PG_FUNCTION_ARGS) { /* If it's really API 1.1, we'll figure that out below */ pg_stat_statements_internal(fcinfo, PGSS_V1_0, true); return (Datum) 0; } /* Common code for all versions of pg_stat_statements() */ static void pg_stat_statements_internal(FunctionCallInfo fcinfo, pgssVersion api_version, bool showtext) { ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo; Oid userid = GetUserId(); bool is_allowed_role = false; char *qbuffer = NULL; Size qbuffer_size = 0; Size extent = 0; int gc_count = 0; HASH_SEQ_STATUS hash_seq; pgssEntry *entry; /* * Superusers or roles with the privileges of pg_read_all_stats members * are allowed */ is_allowed_role = has_privs_of_role(userid, ROLE_PG_READ_ALL_STATS); /* hash table must exist already */ if (!pgss || !pgss_hash) ereport(ERROR, (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), errmsg("pg_stat_statements must be loaded via \"shared_preload_libraries\""))); InitMaterializedSRF(fcinfo, 0); /* * Check we have the expected number of output arguments. Aside from * being a good safety check, we need a kluge here to detect API version * 1.1, which was wedged into the code in an ill-considered way. */ switch (rsinfo->setDesc->natts) { case PG_STAT_STATEMENTS_COLS_V1_0: if (api_version != PGSS_V1_0) elog(ERROR, "incorrect number of output arguments"); break; case PG_STAT_STATEMENTS_COLS_V1_1: /* pg_stat_statements() should have told us 1.0 */ if (api_version != PGSS_V1_0) elog(ERROR, "incorrect number of output arguments"); api_version = PGSS_V1_1; break; case PG_STAT_STATEMENTS_COLS_V1_2: if (api_version != PGSS_V1_2) elog(ERROR, "incorrect number of output arguments"); break; case PG_STAT_STATEMENTS_COLS_V1_3: if (api_version != PGSS_V1_3) elog(ERROR, "incorrect number of output arguments"); break; case PG_STAT_STATEMENTS_COLS_V1_8: if (api_version != PGSS_V1_8) elog(ERROR, "incorrect number of output arguments"); break; case PG_STAT_STATEMENTS_COLS_V1_9: if (api_version != PGSS_V1_9) elog(ERROR, "incorrect number of output arguments"); break; case PG_STAT_STATEMENTS_COLS_V1_10: if (api_version != PGSS_V1_10) elog(ERROR, "incorrect number of output arguments"); break; case PG_STAT_STATEMENTS_COLS_V1_11: if (api_version != PGSS_V1_11) elog(ERROR, "incorrect number of output arguments"); break; default: elog(ERROR, "incorrect number of output arguments"); } /* * We'd like to load the query text file (if needed) while not holding any * lock on pgss->lock. In the worst case we'll have to do this again * after we have the lock, but it's unlikely enough to make this a win * despite occasional duplicated work. We need to reload if anybody * writes to the file (either a retail qtext_store(), or a garbage * collection) between this point and where we've gotten shared lock. If * a qtext_store is actually in progress when we look, we might as well * skip the speculative load entirely. */ if (showtext) { int n_writers; /* Take the mutex so we can examine variables */ { volatile pgssSharedState *s = (volatile pgssSharedState *) pgss; SpinLockAcquire(&s->mutex); extent = s->extent; n_writers = s->n_writers; gc_count = s->gc_count; SpinLockRelease(&s->mutex); } /* No point in loading file now if there are active writers */ if (n_writers == 0) qbuffer = qtext_load_file(&qbuffer_size); } /* * Get shared lock, load or reload the query text file if we must, and * iterate over the hashtable entries. * * With a large hash table, we might be holding the lock rather longer * than one could wish. However, this only blocks creation of new hash * table entries, and the larger the hash table the less likely that is to * be needed. So we can hope this is okay. Perhaps someday we'll decide * we need to partition the hash table to limit the time spent holding any * one lock. */ LWLockAcquire(pgss->lock, LW_SHARED); if (showtext) { /* * Here it is safe to examine extent and gc_count without taking the * mutex. Note that although other processes might change * pgss->extent just after we look at it, the strings they then write * into the file cannot yet be referenced in the hashtable, so we * don't care whether we see them or not. * * If qtext_load_file fails, we just press on; we'll return NULL for * every query text. */ if (qbuffer == NULL || pgss->extent != extent || pgss->gc_count != gc_count) { free(qbuffer); qbuffer = qtext_load_file(&qbuffer_size); } } hash_seq_init(&hash_seq, pgss_hash); while ((entry = hash_seq_search(&hash_seq)) != NULL) { Datum values[PG_STAT_STATEMENTS_COLS]; bool nulls[PG_STAT_STATEMENTS_COLS]; int i = 0; Counters tmp; double stddev; int64 queryid = entry->key.queryid; TimestampTz stats_since; TimestampTz minmax_stats_since; memset(values, 0, sizeof(values)); memset(nulls, 0, sizeof(nulls)); values[i++] = ObjectIdGetDatum(entry->key.userid); values[i++] = ObjectIdGetDatum(entry->key.dbid); if (api_version >= PGSS_V1_9) values[i++] = BoolGetDatum(entry->key.toplevel); if (is_allowed_role || entry->key.userid == userid) { if (api_version >= PGSS_V1_2) values[i++] = Int64GetDatumFast(queryid); if (showtext) { char *qstr = qtext_fetch(entry->query_offset, entry->query_len, qbuffer, qbuffer_size); if (qstr) { char *enc; enc = pg_any_to_server(qstr, entry->query_len, entry->encoding); values[i++] = CStringGetTextDatum(enc); if (enc != qstr) pfree(enc); } else { /* Just return a null if we fail to find the text */ nulls[i++] = true; } } else { /* Query text not requested */ nulls[i++] = true; } } else { /* Don't show queryid */ if (api_version >= PGSS_V1_2) nulls[i++] = true; /* * Don't show query text, but hint as to the reason for not doing * so if it was requested */ if (showtext) values[i++] = CStringGetTextDatum(""); else nulls[i++] = true; } /* copy counters to a local variable to keep locking time short */ { volatile pgssEntry *e = (volatile pgssEntry *) entry; SpinLockAcquire(&e->mutex); tmp = e->counters; stats_since = e->stats_since; minmax_stats_since = e->minmax_stats_since; SpinLockRelease(&e->mutex); } /* Skip entry if unexecuted (ie, it's a pending "sticky" entry) */ if (IS_STICKY(tmp)) continue; /* Note that we rely on PGSS_PLAN being 0 and PGSS_EXEC being 1. */ for (int kind = 0; kind < PGSS_NUMKIND; kind++) { if (kind == PGSS_EXEC || api_version >= PGSS_V1_8) { values[i++] = Int64GetDatumFast(tmp.calls[kind]); values[i++] = Float8GetDatumFast(tmp.total_time[kind]); } if ((kind == PGSS_EXEC && api_version >= PGSS_V1_3) || api_version >= PGSS_V1_8) { values[i++] = Float8GetDatumFast(tmp.min_time[kind]); values[i++] = Float8GetDatumFast(tmp.max_time[kind]); values[i++] = Float8GetDatumFast(tmp.mean_time[kind]); /* * Note we are calculating the population variance here, not * the sample variance, as we have data for the whole * population, so Bessel's correction is not used, and we * don't divide by tmp.calls - 1. */ if (tmp.calls[kind] > 1) stddev = sqrt(tmp.sum_var_time[kind] / tmp.calls[kind]); else stddev = 0.0; values[i++] = Float8GetDatumFast(stddev); } } values[i++] = Int64GetDatumFast(tmp.rows); values[i++] = Int64GetDatumFast(tmp.shared_blks_hit); values[i++] = Int64GetDatumFast(tmp.shared_blks_read); if (api_version >= PGSS_V1_1) values[i++] = Int64GetDatumFast(tmp.shared_blks_dirtied); values[i++] = Int64GetDatumFast(tmp.shared_blks_written); values[i++] = Int64GetDatumFast(tmp.local_blks_hit); values[i++] = Int64GetDatumFast(tmp.local_blks_read); if (api_version >= PGSS_V1_1) values[i++] = Int64GetDatumFast(tmp.local_blks_dirtied); values[i++] = Int64GetDatumFast(tmp.local_blks_written); values[i++] = Int64GetDatumFast(tmp.temp_blks_read); values[i++] = Int64GetDatumFast(tmp.temp_blks_written); if (api_version >= PGSS_V1_1) { values[i++] = Float8GetDatumFast(tmp.shared_blk_read_time); values[i++] = Float8GetDatumFast(tmp.shared_blk_write_time); } if (api_version >= PGSS_V1_11) { values[i++] = Float8GetDatumFast(tmp.local_blk_read_time); values[i++] = Float8GetDatumFast(tmp.local_blk_write_time); } if (api_version >= PGSS_V1_10) { values[i++] = Float8GetDatumFast(tmp.temp_blk_read_time); values[i++] = Float8GetDatumFast(tmp.temp_blk_write_time); } if (api_version >= PGSS_V1_8) { char buf[256]; Datum wal_bytes; values[i++] = Int64GetDatumFast(tmp.wal_records); values[i++] = Int64GetDatumFast(tmp.wal_fpi); snprintf(buf, sizeof buf, UINT64_FORMAT, tmp.wal_bytes); /* Convert to numeric. */ wal_bytes = DirectFunctionCall3(numeric_in, CStringGetDatum(buf), ObjectIdGetDatum(0), Int32GetDatum(-1)); values[i++] = wal_bytes; } if (api_version >= PGSS_V1_10) { values[i++] = Int64GetDatumFast(tmp.jit_functions); values[i++] = Float8GetDatumFast(tmp.jit_generation_time); values[i++] = Int64GetDatumFast(tmp.jit_inlining_count); values[i++] = Float8GetDatumFast(tmp.jit_inlining_time); values[i++] = Int64GetDatumFast(tmp.jit_optimization_count); values[i++] = Float8GetDatumFast(tmp.jit_optimization_time); values[i++] = Int64GetDatumFast(tmp.jit_emission_count); values[i++] = Float8GetDatumFast(tmp.jit_emission_time); } if (api_version >= PGSS_V1_11) { values[i++] = Int64GetDatumFast(tmp.jit_deform_count); values[i++] = Float8GetDatumFast(tmp.jit_deform_time); values[i++] = TimestampTzGetDatum(stats_since); values[i++] = TimestampTzGetDatum(minmax_stats_since); } Assert(i == (api_version == PGSS_V1_0 ? PG_STAT_STATEMENTS_COLS_V1_0 : api_version == PGSS_V1_1 ? PG_STAT_STATEMENTS_COLS_V1_1 : api_version == PGSS_V1_2 ? PG_STAT_STATEMENTS_COLS_V1_2 : api_version == PGSS_V1_3 ? PG_STAT_STATEMENTS_COLS_V1_3 : api_version == PGSS_V1_8 ? PG_STAT_STATEMENTS_COLS_V1_8 : api_version == PGSS_V1_9 ? PG_STAT_STATEMENTS_COLS_V1_9 : api_version == PGSS_V1_10 ? PG_STAT_STATEMENTS_COLS_V1_10 : api_version == PGSS_V1_11 ? PG_STAT_STATEMENTS_COLS_V1_11 : -1 /* fail if you forget to update this assert */ )); tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls); } LWLockRelease(pgss->lock); free(qbuffer); } /* Number of output arguments (columns) for pg_stat_statements_info */ #define PG_STAT_STATEMENTS_INFO_COLS 2 /* * Return statistics of pg_stat_statements. */ Datum pg_stat_statements_info(PG_FUNCTION_ARGS) { pgssGlobalStats stats; TupleDesc tupdesc; Datum values[PG_STAT_STATEMENTS_INFO_COLS] = {0}; bool nulls[PG_STAT_STATEMENTS_INFO_COLS] = {0}; if (!pgss || !pgss_hash) ereport(ERROR, (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), errmsg("pg_stat_statements must be loaded via \"shared_preload_libraries\""))); /* Build a tuple descriptor for our result type */ if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE) elog(ERROR, "return type must be a row type"); /* Read global statistics for pg_stat_statements */ { volatile pgssSharedState *s = (volatile pgssSharedState *) pgss; SpinLockAcquire(&s->mutex); stats = s->stats; SpinLockRelease(&s->mutex); } values[0] = Int64GetDatum(stats.dealloc); values[1] = TimestampTzGetDatum(stats.stats_reset); PG_RETURN_DATUM(HeapTupleGetDatum(heap_form_tuple(tupdesc, values, nulls))); } /* * Estimate shared memory space needed. */ static Size pgss_memsize(void) { Size size; size = MAXALIGN(sizeof(pgssSharedState)); size = add_size(size, hash_estimate_size(pgss_max, sizeof(pgssEntry))); return size; } /* * Allocate a new hashtable entry. * caller must hold an exclusive lock on pgss->lock * * "query" need not be null-terminated; we rely on query_len instead * * If "sticky" is true, make the new entry artificially sticky so that it will * probably still be there when the query finishes execution. We do this by * giving it a median usage value rather than the normal value. (Strictly * speaking, query strings are normalized on a best effort basis, though it * would be difficult to demonstrate this even under artificial conditions.) * * Note: despite needing exclusive lock, it's not an error for the target * entry to already exist. This is because pgss_store releases and * reacquires lock after failing to find a match; so someone else could * have made the entry while we waited to get exclusive lock. */ static pgssEntry * entry_alloc(pgssHashKey *key, Size query_offset, int query_len, int encoding, bool sticky) { pgssEntry *entry; bool found; /* Make space if needed */ while (hash_get_num_entries(pgss_hash) >= pgss_max) entry_dealloc(); /* Find or create an entry with desired hash code */ entry = (pgssEntry *) hash_search(pgss_hash, key, HASH_ENTER, &found); if (!found) { /* New entry, initialize it */ /* reset the statistics */ memset(&entry->counters, 0, sizeof(Counters)); /* set the appropriate initial usage count */ entry->counters.usage = sticky ? pgss->cur_median_usage : USAGE_INIT; /* re-initialize the mutex each time ... we assume no one using it */ SpinLockInit(&entry->mutex); /* ... and don't forget the query text metadata */ Assert(query_len >= 0); entry->query_offset = query_offset; entry->query_len = query_len; entry->encoding = encoding; entry->stats_since = GetCurrentTimestamp(); entry->minmax_stats_since = entry->stats_since; } return entry; } /* * qsort comparator for sorting into increasing usage order */ static int entry_cmp(const void *lhs, const void *rhs) { double l_usage = (*(pgssEntry *const *) lhs)->counters.usage; double r_usage = (*(pgssEntry *const *) rhs)->counters.usage; if (l_usage < r_usage) return -1; else if (l_usage > r_usage) return +1; else return 0; } /* * Deallocate least-used entries. * * Caller must hold an exclusive lock on pgss->lock. */ static void entry_dealloc(void) { HASH_SEQ_STATUS hash_seq; pgssEntry **entries; pgssEntry *entry; int nvictims; int i; Size tottextlen; int nvalidtexts; /* * Sort entries by usage and deallocate USAGE_DEALLOC_PERCENT of them. * While we're scanning the table, apply the decay factor to the usage * values, and update the mean query length. * * Note that the mean query length is almost immediately obsolete, since * we compute it before not after discarding the least-used entries. * Hopefully, that doesn't affect the mean too much; it doesn't seem worth * making two passes to get a more current result. Likewise, the new * cur_median_usage includes the entries we're about to zap. */ entries = palloc(hash_get_num_entries(pgss_hash) * sizeof(pgssEntry *)); i = 0; tottextlen = 0; nvalidtexts = 0; hash_seq_init(&hash_seq, pgss_hash); while ((entry = hash_seq_search(&hash_seq)) != NULL) { entries[i++] = entry; /* "Sticky" entries get a different usage decay rate. */ if (IS_STICKY(entry->counters)) entry->counters.usage *= STICKY_DECREASE_FACTOR; else entry->counters.usage *= USAGE_DECREASE_FACTOR; /* In the mean length computation, ignore dropped texts. */ if (entry->query_len >= 0) { tottextlen += entry->query_len + 1; nvalidtexts++; } } /* Sort into increasing order by usage */ qsort(entries, i, sizeof(pgssEntry *), entry_cmp); /* Record the (approximate) median usage */ if (i > 0) pgss->cur_median_usage = entries[i / 2]->counters.usage; /* Record the mean query length */ if (nvalidtexts > 0) pgss->mean_query_len = tottextlen / nvalidtexts; else pgss->mean_query_len = ASSUMED_LENGTH_INIT; /* Now zap an appropriate fraction of lowest-usage entries */ nvictims = Max(10, i * USAGE_DEALLOC_PERCENT / 100); nvictims = Min(nvictims, i); for (i = 0; i < nvictims; i++) { hash_search(pgss_hash, &entries[i]->key, HASH_REMOVE, NULL); } pfree(entries); /* Increment the number of times entries are deallocated */ { volatile pgssSharedState *s = (volatile pgssSharedState *) pgss; SpinLockAcquire(&s->mutex); s->stats.dealloc += 1; SpinLockRelease(&s->mutex); } } /* * Given a query string (not necessarily null-terminated), allocate a new * entry in the external query text file and store the string there. * * If successful, returns true, and stores the new entry's offset in the file * into *query_offset. Also, if gc_count isn't NULL, *gc_count is set to the * number of garbage collections that have occurred so far. * * On failure, returns false. * * At least a shared lock on pgss->lock must be held by the caller, so as * to prevent a concurrent garbage collection. Share-lock-holding callers * should pass a gc_count pointer to obtain the number of garbage collections, * so that they can recheck the count after obtaining exclusive lock to * detect whether a garbage collection occurred (and removed this entry). */ static bool qtext_store(const char *query, int query_len, Size *query_offset, int *gc_count) { Size off; int fd; /* * We use a spinlock to protect extent/n_writers/gc_count, so that * multiple processes may execute this function concurrently. */ { volatile pgssSharedState *s = (volatile pgssSharedState *) pgss; SpinLockAcquire(&s->mutex); off = s->extent; s->extent += query_len + 1; s->n_writers++; if (gc_count) *gc_count = s->gc_count; SpinLockRelease(&s->mutex); } *query_offset = off; /* * Don't allow the file to grow larger than what qtext_load_file can * (theoretically) handle. This has been seen to be reachable on 32-bit * platforms. */ if (unlikely(query_len >= MaxAllocHugeSize - off)) { errno = EFBIG; /* not quite right, but it'll do */ fd = -1; goto error; } /* Now write the data into the successfully-reserved part of the file */ fd = OpenTransientFile(PGSS_TEXT_FILE, O_RDWR | O_CREAT | PG_BINARY); if (fd < 0) goto error; if (pg_pwrite(fd, query, query_len, off) != query_len) goto error; if (pg_pwrite(fd, "\0", 1, off + query_len) != 1) goto error; CloseTransientFile(fd); /* Mark our write complete */ { volatile pgssSharedState *s = (volatile pgssSharedState *) pgss; SpinLockAcquire(&s->mutex); s->n_writers--; SpinLockRelease(&s->mutex); } return true; error: ereport(LOG, (errcode_for_file_access(), errmsg("could not write file \"%s\": %m", PGSS_TEXT_FILE))); if (fd >= 0) CloseTransientFile(fd); /* Mark our write complete */ { volatile pgssSharedState *s = (volatile pgssSharedState *) pgss; SpinLockAcquire(&s->mutex); s->n_writers--; SpinLockRelease(&s->mutex); } return false; } /* * Read the external query text file into a malloc'd buffer. * * Returns NULL (without throwing an error) if unable to read, eg * file not there or insufficient memory. * * On success, the buffer size is also returned into *buffer_size. * * This can be called without any lock on pgss->lock, but in that case * the caller is responsible for verifying that the result is sane. */ static char * qtext_load_file(Size *buffer_size) { char *buf; int fd; struct stat stat; Size nread; fd = OpenTransientFile(PGSS_TEXT_FILE, O_RDONLY | PG_BINARY); if (fd < 0) { if (errno != ENOENT) ereport(LOG, (errcode_for_file_access(), errmsg("could not read file \"%s\": %m", PGSS_TEXT_FILE))); return NULL; } /* Get file length */ if (fstat(fd, &stat)) { ereport(LOG, (errcode_for_file_access(), errmsg("could not stat file \"%s\": %m", PGSS_TEXT_FILE))); CloseTransientFile(fd); return NULL; } /* Allocate buffer; beware that off_t might be wider than size_t */ if (stat.st_size <= MaxAllocHugeSize) buf = (char *) malloc(stat.st_size); else buf = NULL; if (buf == NULL) { ereport(LOG, (errcode(ERRCODE_OUT_OF_MEMORY), errmsg("out of memory"), errdetail("Could not allocate enough memory to read file \"%s\".", PGSS_TEXT_FILE))); CloseTransientFile(fd); return NULL; } /* * OK, slurp in the file. Windows fails if we try to read more than * INT_MAX bytes at once, and other platforms might not like that either, * so read a very large file in 1GB segments. */ nread = 0; while (nread < stat.st_size) { int toread = Min(1024 * 1024 * 1024, stat.st_size - nread); /* * If we get a short read and errno doesn't get set, the reason is * probably that garbage collection truncated the file since we did * the fstat(), so we don't log a complaint --- but we don't return * the data, either, since it's most likely corrupt due to concurrent * writes from garbage collection. */ errno = 0; if (read(fd, buf + nread, toread) != toread) { if (errno) ereport(LOG, (errcode_for_file_access(), errmsg("could not read file \"%s\": %m", PGSS_TEXT_FILE))); free(buf); CloseTransientFile(fd); return NULL; } nread += toread; } if (CloseTransientFile(fd) != 0) ereport(LOG, (errcode_for_file_access(), errmsg("could not close file \"%s\": %m", PGSS_TEXT_FILE))); *buffer_size = nread; return buf; } /* * Locate a query text in the file image previously read by qtext_load_file(). * * We validate the given offset/length, and return NULL if bogus. Otherwise, * the result points to a null-terminated string within the buffer. */ static char * qtext_fetch(Size query_offset, int query_len, char *buffer, Size buffer_size) { /* File read failed? */ if (buffer == NULL) return NULL; /* Bogus offset/length? */ if (query_len < 0 || query_offset + query_len >= buffer_size) return NULL; /* As a further sanity check, make sure there's a trailing null */ if (buffer[query_offset + query_len] != '\0') return NULL; /* Looks OK */ return buffer + query_offset; } /* * Do we need to garbage-collect the external query text file? * * Caller should hold at least a shared lock on pgss->lock. */ static bool need_gc_qtexts(void) { Size extent; /* Read shared extent pointer */ { volatile pgssSharedState *s = (volatile pgssSharedState *) pgss; SpinLockAcquire(&s->mutex); extent = s->extent; SpinLockRelease(&s->mutex); } /* * Don't proceed if file does not exceed 512 bytes per possible entry. * * Here and in the next test, 32-bit machines have overflow hazards if * pgss_max and/or mean_query_len are large. Force the multiplications * and comparisons to be done in uint64 arithmetic to forestall trouble. */ if ((uint64) extent < (uint64) 512 * pgss_max) return false; /* * Don't proceed if file is less than about 50% bloat. Nothing can or * should be done in the event of unusually large query texts accounting * for file's large size. We go to the trouble of maintaining the mean * query length in order to prevent garbage collection from thrashing * uselessly. */ if ((uint64) extent < (uint64) pgss->mean_query_len * pgss_max * 2) return false; return true; } /* * Garbage-collect orphaned query texts in external file. * * This won't be called often in the typical case, since it's likely that * there won't be too much churn, and besides, a similar compaction process * occurs when serializing to disk at shutdown or as part of resetting. * Despite this, it seems prudent to plan for the edge case where the file * becomes unreasonably large, with no other method of compaction likely to * occur in the foreseeable future. * * The caller must hold an exclusive lock on pgss->lock. * * At the first sign of trouble we unlink the query text file to get a clean * slate (although existing statistics are retained), rather than risk * thrashing by allowing the same problem case to recur indefinitely. */ static void gc_qtexts(void) { char *qbuffer; Size qbuffer_size; FILE *qfile = NULL; HASH_SEQ_STATUS hash_seq; pgssEntry *entry; Size extent; int nentries; /* * When called from pgss_store, some other session might have proceeded * with garbage collection in the no-lock-held interim of lock strength * escalation. Check once more that this is actually necessary. */ if (!need_gc_qtexts()) return; /* * Load the old texts file. If we fail (out of memory, for instance), * invalidate query texts. Hopefully this is rare. It might seem better * to leave things alone on an OOM failure, but the problem is that the * file is only going to get bigger; hoping for a future non-OOM result is * risky and can easily lead to complete denial of service. */ qbuffer = qtext_load_file(&qbuffer_size); if (qbuffer == NULL) goto gc_fail; /* * We overwrite the query texts file in place, so as to reduce the risk of * an out-of-disk-space failure. Since the file is guaranteed not to get * larger, this should always work on traditional filesystems; though we * could still lose on copy-on-write filesystems. */ qfile = AllocateFile(PGSS_TEXT_FILE, PG_BINARY_W); if (qfile == NULL) { ereport(LOG, (errcode_for_file_access(), errmsg("could not write file \"%s\": %m", PGSS_TEXT_FILE))); goto gc_fail; } extent = 0; nentries = 0; hash_seq_init(&hash_seq, pgss_hash); while ((entry = hash_seq_search(&hash_seq)) != NULL) { int query_len = entry->query_len; char *qry = qtext_fetch(entry->query_offset, query_len, qbuffer, qbuffer_size); if (qry == NULL) { /* Trouble ... drop the text */ entry->query_offset = 0; entry->query_len = -1; /* entry will not be counted in mean query length computation */ continue; } if (fwrite(qry, 1, query_len + 1, qfile) != query_len + 1) { ereport(LOG, (errcode_for_file_access(), errmsg("could not write file \"%s\": %m", PGSS_TEXT_FILE))); hash_seq_term(&hash_seq); goto gc_fail; } entry->query_offset = extent; extent += query_len + 1; nentries++; } /* * Truncate away any now-unused space. If this fails for some odd reason, * we log it, but there's no need to fail. */ if (ftruncate(fileno(qfile), extent) != 0) ereport(LOG, (errcode_for_file_access(), errmsg("could not truncate file \"%s\": %m", PGSS_TEXT_FILE))); if (FreeFile(qfile)) { ereport(LOG, (errcode_for_file_access(), errmsg("could not write file \"%s\": %m", PGSS_TEXT_FILE))); qfile = NULL; goto gc_fail; } elog(DEBUG1, "pgss gc of queries file shrunk size from %zu to %zu", pgss->extent, extent); /* Reset the shared extent pointer */ pgss->extent = extent; /* * Also update the mean query length, to be sure that need_gc_qtexts() * won't still think we have a problem. */ if (nentries > 0) pgss->mean_query_len = extent / nentries; else pgss->mean_query_len = ASSUMED_LENGTH_INIT; free(qbuffer); /* * OK, count a garbage collection cycle. (Note: even though we have * exclusive lock on pgss->lock, we must take pgss->mutex for this, since * other processes may examine gc_count while holding only the mutex. * Also, we have to advance the count *after* we've rewritten the file, * else other processes might not realize they read a stale file.) */ record_gc_qtexts(); return; gc_fail: /* clean up resources */ if (qfile) FreeFile(qfile); free(qbuffer); /* * Since the contents of the external file are now uncertain, mark all * hashtable entries as having invalid texts. */ hash_seq_init(&hash_seq, pgss_hash); while ((entry = hash_seq_search(&hash_seq)) != NULL) { entry->query_offset = 0; entry->query_len = -1; } /* * Destroy the query text file and create a new, empty one */ (void) unlink(PGSS_TEXT_FILE); qfile = AllocateFile(PGSS_TEXT_FILE, PG_BINARY_W); if (qfile == NULL) ereport(LOG, (errcode_for_file_access(), errmsg("could not recreate file \"%s\": %m", PGSS_TEXT_FILE))); else FreeFile(qfile); /* Reset the shared extent pointer */ pgss->extent = 0; /* Reset mean_query_len to match the new state */ pgss->mean_query_len = ASSUMED_LENGTH_INIT; /* * Bump the GC count even though we failed. * * This is needed to make concurrent readers of file without any lock on * pgss->lock notice existence of new version of file. Once readers * subsequently observe a change in GC count with pgss->lock held, that * forces a safe reopen of file. Writers also require that we bump here, * of course. (As required by locking protocol, readers and writers don't * trust earlier file contents until gc_count is found unchanged after * pgss->lock acquired in shared or exclusive mode respectively.) */ record_gc_qtexts(); } #define SINGLE_ENTRY_RESET(e) \ if (e) { \ if (minmax_only) { \ /* When requested reset only min/max statistics of an entry */ \ for (int kind = 0; kind < PGSS_NUMKIND; kind++) \ { \ e->counters.max_time[kind] = 0; \ e->counters.min_time[kind] = 0; \ } \ e->minmax_stats_since = stats_reset; \ } \ else \ { \ /* Remove the key otherwise */ \ hash_search(pgss_hash, &e->key, HASH_REMOVE, NULL); \ num_remove++; \ } \ } /* * Reset entries corresponding to parameters passed. */ static TimestampTz entry_reset(Oid userid, Oid dbid, uint64 queryid, bool minmax_only) { HASH_SEQ_STATUS hash_seq; pgssEntry *entry; FILE *qfile; long num_entries; long num_remove = 0; pgssHashKey key; TimestampTz stats_reset; if (!pgss || !pgss_hash) ereport(ERROR, (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), errmsg("pg_stat_statements must be loaded via \"shared_preload_libraries\""))); LWLockAcquire(pgss->lock, LW_EXCLUSIVE); num_entries = hash_get_num_entries(pgss_hash); stats_reset = GetCurrentTimestamp(); if (userid != 0 && dbid != 0 && queryid != UINT64CONST(0)) { /* If all the parameters are available, use the fast path. */ memset(&key, 0, sizeof(pgssHashKey)); key.userid = userid; key.dbid = dbid; key.queryid = queryid; /* * Reset the entry if it exists, starting with the non-top-level * entry. */ key.toplevel = false; entry = (pgssEntry *) hash_search(pgss_hash, &key, HASH_FIND, NULL); SINGLE_ENTRY_RESET(entry); /* Also reset the top-level entry if it exists. */ key.toplevel = true; entry = (pgssEntry *) hash_search(pgss_hash, &key, HASH_FIND, NULL); SINGLE_ENTRY_RESET(entry); } else if (userid != 0 || dbid != 0 || queryid != UINT64CONST(0)) { /* Reset entries corresponding to valid parameters. */ hash_seq_init(&hash_seq, pgss_hash); while ((entry = hash_seq_search(&hash_seq)) != NULL) { if ((!userid || entry->key.userid == userid) && (!dbid || entry->key.dbid == dbid) && (!queryid || entry->key.queryid == queryid)) { SINGLE_ENTRY_RESET(entry); } } } else { /* Reset all entries. */ hash_seq_init(&hash_seq, pgss_hash); while ((entry = hash_seq_search(&hash_seq)) != NULL) { SINGLE_ENTRY_RESET(entry); } } /* All entries are removed? */ if (num_entries != num_remove) goto release_lock; /* * Reset global statistics for pg_stat_statements since all entries are * removed. */ { volatile pgssSharedState *s = (volatile pgssSharedState *) pgss; SpinLockAcquire(&s->mutex); s->stats.dealloc = 0; s->stats.stats_reset = stats_reset; SpinLockRelease(&s->mutex); } /* * Write new empty query file, perhaps even creating a new one to recover * if the file was missing. */ qfile = AllocateFile(PGSS_TEXT_FILE, PG_BINARY_W); if (qfile == NULL) { ereport(LOG, (errcode_for_file_access(), errmsg("could not create file \"%s\": %m", PGSS_TEXT_FILE))); goto done; } /* If ftruncate fails, log it, but it's not a fatal problem */ if (ftruncate(fileno(qfile), 0) != 0) ereport(LOG, (errcode_for_file_access(), errmsg("could not truncate file \"%s\": %m", PGSS_TEXT_FILE))); FreeFile(qfile); done: pgss->extent = 0; /* This counts as a query text garbage collection for our purposes */ record_gc_qtexts(); release_lock: LWLockRelease(pgss->lock); return stats_reset; } /* * Generate a normalized version of the query string that will be used to * represent all similar queries. * * Note that the normalized representation may well vary depending on * just which "equivalent" query is used to create the hashtable entry. * We assume this is OK. * * If query_loc > 0, then "query" has been advanced by that much compared to * the original string start, so we need to translate the provided locations * to compensate. (This lets us avoid re-scanning statements before the one * of interest, so it's worth doing.) * * *query_len_p contains the input string length, and is updated with * the result string length on exit. The resulting string might be longer * or shorter depending on what happens with replacement of constants. * * Returns a palloc'd string. */ static char * generate_normalized_query(JumbleState *jstate, const char *query, int query_loc, int *query_len_p) { char *norm_query; int query_len = *query_len_p; int i, norm_query_buflen, /* Space allowed for norm_query */ len_to_wrt, /* Length (in bytes) to write */ quer_loc = 0, /* Source query byte location */ n_quer_loc = 0, /* Normalized query byte location */ last_off = 0, /* Offset from start for previous tok */ last_tok_len = 0; /* Length (in bytes) of that tok */ /* * Get constants' lengths (core system only gives us locations). Note * this also ensures the items are sorted by location. */ fill_in_constant_lengths(jstate, query, query_loc); /* * Allow for $n symbols to be longer than the constants they replace. * Constants must take at least one byte in text form, while a $n symbol * certainly isn't more than 11 bytes, even if n reaches INT_MAX. We * could refine that limit based on the max value of n for the current * query, but it hardly seems worth any extra effort to do so. */ norm_query_buflen = query_len + jstate->clocations_count * 10; /* Allocate result buffer */ norm_query = palloc(norm_query_buflen + 1); for (i = 0; i < jstate->clocations_count; i++) { int off, /* Offset from start for cur tok */ tok_len; /* Length (in bytes) of that tok */ off = jstate->clocations[i].location; /* Adjust recorded location if we're dealing with partial string */ off -= query_loc; tok_len = jstate->clocations[i].length; if (tok_len < 0) continue; /* ignore any duplicates */ /* Copy next chunk (what precedes the next constant) */ len_to_wrt = off - last_off; len_to_wrt -= last_tok_len; Assert(len_to_wrt >= 0); memcpy(norm_query + n_quer_loc, query + quer_loc, len_to_wrt); n_quer_loc += len_to_wrt; /* And insert a param symbol in place of the constant token */ n_quer_loc += sprintf(norm_query + n_quer_loc, "$%d", i + 1 + jstate->highest_extern_param_id); quer_loc = off + tok_len; last_off = off; last_tok_len = tok_len; } /* * We've copied up until the last ignorable constant. Copy over the * remaining bytes of the original query string. */ len_to_wrt = query_len - quer_loc; Assert(len_to_wrt >= 0); memcpy(norm_query + n_quer_loc, query + quer_loc, len_to_wrt); n_quer_loc += len_to_wrt; Assert(n_quer_loc <= norm_query_buflen); norm_query[n_quer_loc] = '\0'; *query_len_p = n_quer_loc; return norm_query; } /* * Given a valid SQL string and an array of constant-location records, * fill in the textual lengths of those constants. * * The constants may use any allowed constant syntax, such as float literals, * bit-strings, single-quoted strings and dollar-quoted strings. This is * accomplished by using the public API for the core scanner. * * It is the caller's job to ensure that the string is a valid SQL statement * with constants at the indicated locations. Since in practice the string * has already been parsed, and the locations that the caller provides will * have originated from within the authoritative parser, this should not be * a problem. * * Duplicate constant pointers are possible, and will have their lengths * marked as '-1', so that they are later ignored. (Actually, we assume the * lengths were initialized as -1 to start with, and don't change them here.) * * If query_loc > 0, then "query" has been advanced by that much compared to * the original string start, so we need to translate the provided locations * to compensate. (This lets us avoid re-scanning statements before the one * of interest, so it's worth doing.) * * N.B. There is an assumption that a '-' character at a Const location begins * a negative numeric constant. This precludes there ever being another * reason for a constant to start with a '-'. */ static void fill_in_constant_lengths(JumbleState *jstate, const char *query, int query_loc) { LocationLen *locs; core_yyscan_t yyscanner; core_yy_extra_type yyextra; core_YYSTYPE yylval; YYLTYPE yylloc; int last_loc = -1; int i; /* * Sort the records by location so that we can process them in order while * scanning the query text. */ if (jstate->clocations_count > 1) qsort(jstate->clocations, jstate->clocations_count, sizeof(LocationLen), comp_location); locs = jstate->clocations; /* initialize the flex scanner --- should match raw_parser() */ yyscanner = scanner_init(query, &yyextra, &ScanKeywords, ScanKeywordTokens); /* we don't want to re-emit any escape string warnings */ yyextra.escape_string_warning = false; /* Search for each constant, in sequence */ for (i = 0; i < jstate->clocations_count; i++) { int loc = locs[i].location; int tok; /* Adjust recorded location if we're dealing with partial string */ loc -= query_loc; Assert(loc >= 0); if (loc <= last_loc) continue; /* Duplicate constant, ignore */ /* Lex tokens until we find the desired constant */ for (;;) { tok = core_yylex(&yylval, &yylloc, yyscanner); /* We should not hit end-of-string, but if we do, behave sanely */ if (tok == 0) break; /* out of inner for-loop */ /* * We should find the token position exactly, but if we somehow * run past it, work with that. */ if (yylloc >= loc) { if (query[loc] == '-') { /* * It's a negative value - this is the one and only case * where we replace more than a single token. * * Do not compensate for the core system's special-case * adjustment of location to that of the leading '-' * operator in the event of a negative constant. It is * also useful for our purposes to start from the minus * symbol. In this way, queries like "select * from foo * where bar = 1" and "select * from foo where bar = -2" * will have identical normalized query strings. */ tok = core_yylex(&yylval, &yylloc, yyscanner); if (tok == 0) break; /* out of inner for-loop */ } /* * We now rely on the assumption that flex has placed a zero * byte after the text of the current token in scanbuf. */ locs[i].length = strlen(yyextra.scanbuf + loc); break; /* out of inner for-loop */ } } /* If we hit end-of-string, give up, leaving remaining lengths -1 */ if (tok == 0) break; last_loc = loc; } scanner_finish(yyscanner); } /* * comp_location: comparator for qsorting LocationLen structs by location */ static int comp_location(const void *a, const void *b) { int l = ((const LocationLen *) a)->location; int r = ((const LocationLen *) b)->location; return pg_cmp_s32(l, r); }