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postgresql/contrib/pg_stat_statements/pg_stat_statements.c
Heikki Linnakangas 3cd934f635 Don't track DEALLOCATE in pg_stat_statements. 
We also don't track PREPARE, nor do we track planning time in general, so
let's ignore DEALLOCATE as well for consistency.

Backpatch to 9.4, but not further than that. Although it seems unlikely that
anyone is relying on the current behavior, this is a behavioral change.

Fabien Coelho
2014-08-25 19:13:24 +03:00

2899 lines
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/*-------------------------------------------------------------------------
*
* pg_stat_statements.c
* Track statement execution times across a whole database cluster.
*
* Execution costs are totalled 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.)
*
* As of Postgres 9.2, this module normalizes query entries. Normalization
* is a process whereby similar queries, typically differing only in their
* constants (though the exact rules are somewhat more subtle than that) are
* recognized as equivalent, and are tracked as a single entry. This is
* particularly useful for non-prepared queries.
*
* Normalization is implemented by fingerprinting queries, selectively
* serializing those fields of each query tree's nodes that are judged to be
* essential to the query. This is referred to as a query jumble. This is
* distinct from a regular serialization in that various extraneous
* information is ignored as irrelevant or not essential to the query, such
* as the collations of Vars and, most notably, the values of constants.
*
* This jumble is acquired at the end of parse analysis of each query, and
* a 32-bit hash of it is stored into the query's Query.queryId field.
* The server then copies this value around, making it available in plan
* tree(s) generated from the query. The executor can then use this value
* to blame query costs on the proper queryId.
*
* To facilitate presenting entries to users, we create "representative" query
* strings in which constants are replaced with '?' characters, 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) 2008-2014, PostgreSQL Global Development Group
*
* IDENTIFICATION
* contrib/pg_stat_statements/pg_stat_statements.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include <sys/stat.h>
#include <unistd.h>
#include "access/hash.h"
#include "executor/instrument.h"
#include "funcapi.h"
#include "mb/pg_wchar.h"
#include "miscadmin.h"
#include "parser/analyze.h"
#include "parser/parsetree.h"
#include "parser/scanner.h"
#include "pgstat.h"
#include "storage/fd.h"
#include "storage/ipc.h"
#include "storage/spin.h"
#include "tcop/utility.h"
#include "utils/builtins.h"
#include "utils/memutils.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. We don't keep it in the core
* system's stats_temp_directory. The core system can safely use that GUC
* setting, because the statistics collector temp file paths are set only once
* as part of changing the GUC, but pg_stat_statements has no way of avoiding
* race conditions. Besides, we only expect modest, infrequent I/O for query
* strings, so placing the file on a faster filesystem is not compelling.
*/
#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 = 0x20140125;
/* 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 JUMBLE_SIZE 1024 /* query serialization buffer size */
/*
* Extension version number, for supporting older extension versions' objects
*/
typedef enum pgssVersion
{
PGSS_V1_0 = 0,
PGSS_V1_1,
PGSS_V1_2
} pgssVersion;
/*
* Hashtable key that defines the identity of a hashtable entry. We separate
* queries by user and by database even if they are otherwise identical.
*/
typedef struct pgssHashKey
{
Oid userid; /* user OID */
Oid dbid; /* database OID */
uint32 queryid; /* query identifier */
} pgssHashKey;
/*
* The actual stats counters kept within pgssEntry.
*/
typedef struct Counters
{
int64 calls; /* # of times executed */
double total_time; /* total 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 blk_read_time; /* time spent reading, in msec */
double blk_write_time; /* time spent writing, in msec */
double usage; /* usage factor */
} Counters;
/*
* 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 */
int encoding; /* query text encoding */
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 */
} pgssSharedState;
/*
* Struct for tracking locations/lengths of constants during normalization
*/
typedef struct pgssLocationLen
{
int location; /* start offset in query text */
int length; /* length in bytes, or -1 to ignore */
} pgssLocationLen;
/*
* Working state for computing a query jumble and producing a normalized
* query string
*/
typedef struct pgssJumbleState
{
/* 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 */
pgssLocationLen *clocations;
/* Allocated length of clocations array */
int clocations_buf_size;
/* Current number of valid entries in clocations array */
int clocations_count;
} pgssJumbleState;
/*---- Local variables ----*/
/* Current nesting depth of ExecutorRun+ProcessUtility calls */
static int nested_level = 0;
/* Saved hook values in case of unload */
static shmem_startup_hook_type prev_shmem_startup_hook = NULL;
static post_parse_analyze_hook_type prev_post_parse_analyze_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; /* max # statements to track */
static int pgss_track; /* tracking level */
static bool pgss_track_utility; /* whether to track utility commands */
static bool pgss_save; /* whether to save stats across shutdown */
#define pgss_enabled() \
(pgss_track == PGSS_TRACK_ALL || \
(pgss_track == PGSS_TRACK_TOP && nested_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 ----*/
void _PG_init(void);
void _PG_fini(void);
PG_FUNCTION_INFO_V1(pg_stat_statements_reset);
PG_FUNCTION_INFO_V1(pg_stat_statements_1_2);
PG_FUNCTION_INFO_V1(pg_stat_statements);
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);
static void pgss_ExecutorStart(QueryDesc *queryDesc, int eflags);
static void pgss_ExecutorRun(QueryDesc *queryDesc,
ScanDirection direction,
long count);
static void pgss_ExecutorFinish(QueryDesc *queryDesc);
static void pgss_ExecutorEnd(QueryDesc *queryDesc);
static void pgss_ProcessUtility(Node *parsetree, const char *queryString,
ProcessUtilityContext context, ParamListInfo params,
DestReceiver *dest, char *completionTag);
static uint32 pgss_hash_fn(const void *key, Size keysize);
static int pgss_match_fn(const void *key1, const void *key2, Size keysize);
static uint32 pgss_hash_string(const char *str);
static void pgss_store(const char *query, uint32 queryId,
double total_time, uint64 rows,
const BufferUsage *bufusage,
pgssJumbleState *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 void entry_reset(void);
static void AppendJumble(pgssJumbleState *jstate,
const unsigned char *item, Size size);
static void JumbleQuery(pgssJumbleState *jstate, Query *query);
static void JumbleRangeTable(pgssJumbleState *jstate, List *rtable);
static void JumbleExpr(pgssJumbleState *jstate, Node *node);
static void RecordConstLocation(pgssJumbleState *jstate, int location);
static char *generate_normalized_query(pgssJumbleState *jstate, const char *query,
int *query_len_p, int encoding);
static void fill_in_constant_lengths(pgssJumbleState *jstate, const char *query);
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;
/*
* 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,
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.save",
"Save pg_stat_statements statistics across server shutdowns.",
NULL,
&pgss_save,
true,
PGC_SIGHUP,
0,
NULL,
NULL,
NULL);
EmitWarningsOnPlaceholders("pg_stat_statements");
/*
* Request additional shared resources. (These are no-ops if we're not in
* the postmaster process.) We'll allocate or attach to the shared
* resources in pgss_shmem_startup().
*/
RequestAddinShmemSpace(pgss_memsize());
RequestAddinLWLocks(1);
/*
* Install hooks.
*/
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_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;
}
/*
* Module unload callback
*/
void
_PG_fini(void)
{
/* Uninstall hooks. */
shmem_startup_hook = prev_shmem_startup_hook;
post_parse_analyze_hook = prev_post_parse_analyze_hook;
ExecutorStart_hook = prev_ExecutorStart;
ExecutorRun_hook = prev_ExecutorRun;
ExecutorFinish_hook = prev_ExecutorFinish;
ExecutorEnd_hook = prev_ExecutorEnd;
ProcessUtility_hook = prev_ProcessUtility;
}
/*
* 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 = LWLockAssign();
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;
}
memset(&info, 0, sizeof(info));
info.keysize = sizeof(pgssHashKey);
info.entrysize = sizeof(pgssEntry);
info.hash = pgss_hash_fn;
info.match = pgss_match_fn;
pgss_hash = ShmemInitHash("pg_stat_statements hash",
pgss_max, pgss_max,
&info,
HASH_ELEM | HASH_FUNCTION | HASH_COMPARE);
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 (temp.counters.calls == 0)
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;
}
pfree(buffer);
FreeFile(file);
FreeFile(qfile);
/*
* Remove the persisted stats file so it's not included in
* backups/replication slaves, 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 pg_stat_statement file \"%s\": %m",
PGSS_DUMP_FILE)));
goto fail;
data_error:
ereport(LOG,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("ignoring invalid data in pg_stat_statement file \"%s\"",
PGSS_DUMP_FILE)));
goto fail;
write_error:
ereport(LOG,
(errcode_for_file_access(),
errmsg("could not write pg_stat_statement 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;
}
}
free(qbuffer);
qbuffer = NULL;
if (FreeFile(file))
{
file = NULL;
goto error;
}
/*
* Rename file into place, so we atomically replace any old one.
*/
if (rename(PGSS_DUMP_FILE ".tmp", PGSS_DUMP_FILE) != 0)
ereport(LOG,
(errcode_for_file_access(),
errmsg("could not rename pg_stat_statement file \"%s\": %m",
PGSS_DUMP_FILE ".tmp")));
/* 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 pg_stat_statement file \"%s\": %m",
PGSS_DUMP_FILE ".tmp")));
if (qbuffer)
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)
{
pgssJumbleState jstate;
if (prev_post_parse_analyze_hook)
prev_post_parse_analyze_hook(pstate, query);
/* Assert we didn't do this already */
Assert(query->queryId == 0);
/* Safety check... */
if (!pgss || !pgss_hash)
return;
/*
* Utility statements 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.
*/
if (query->utilityStmt)
{
query->queryId = 0;
return;
}
/* Set up workspace for query jumbling */
jstate.jumble = (unsigned char *) palloc(JUMBLE_SIZE);
jstate.jumble_len = 0;
jstate.clocations_buf_size = 32;
jstate.clocations = (pgssLocationLen *)
palloc(jstate.clocations_buf_size * sizeof(pgssLocationLen));
jstate.clocations_count = 0;
/* Compute query ID and mark the Query node with it */
JumbleQuery(&jstate, query);
query->queryId = hash_any(jstate.jumble, jstate.jumble_len);
/*
* If we are unlucky enough to get a hash of zero, use 1 instead, to
* prevent confusion with the utility-statement case.
*/
if (query->queryId == 0)
query->queryId = 1;
/*
* If we 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.clocations_count > 0)
pgss_store(pstate->p_sourcetext,
query->queryId,
0,
0,
NULL,
&jstate);
}
/*
* 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() && queryDesc->plannedstmt->queryId != 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);
MemoryContextSwitchTo(oldcxt);
}
}
}
/*
* ExecutorRun hook: all we need do is track nesting depth
*/
static void
pgss_ExecutorRun(QueryDesc *queryDesc, ScanDirection direction, long count)
{
nested_level++;
PG_TRY();
{
if (prev_ExecutorRun)
prev_ExecutorRun(queryDesc, direction, count);
else
standard_ExecutorRun(queryDesc, direction, count);
nested_level--;
}
PG_CATCH();
{
nested_level--;
PG_RE_THROW();
}
PG_END_TRY();
}
/*
* ExecutorFinish hook: all we need do is track nesting depth
*/
static void
pgss_ExecutorFinish(QueryDesc *queryDesc)
{
nested_level++;
PG_TRY();
{
if (prev_ExecutorFinish)
prev_ExecutorFinish(queryDesc);
else
standard_ExecutorFinish(queryDesc);
nested_level--;
}
PG_CATCH();
{
nested_level--;
PG_RE_THROW();
}
PG_END_TRY();
}
/*
* ExecutorEnd hook: store results if needed
*/
static void
pgss_ExecutorEnd(QueryDesc *queryDesc)
{
uint32 queryId = queryDesc->plannedstmt->queryId;
if (queryId != 0 && queryDesc->totaltime && pgss_enabled())
{
/*
* 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->totaltime->total * 1000.0, /* convert to msec */
queryDesc->estate->es_processed,
&queryDesc->totaltime->bufusage,
NULL);
}
if (prev_ExecutorEnd)
prev_ExecutorEnd(queryDesc);
else
standard_ExecutorEnd(queryDesc);
}
/*
* ProcessUtility hook
*/
static void
pgss_ProcessUtility(Node *parsetree, const char *queryString,
ProcessUtilityContext context, ParamListInfo params,
DestReceiver *dest, char *completionTag)
{
/*
* 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, and inconsistent with other
* cases where planning time is not included at all.
*
* Likewise, we don't track execution of DEALLOCATE.
*/
if (pgss_track_utility && pgss_enabled() &&
!IsA(parsetree, ExecuteStmt) &&
!IsA(parsetree, PrepareStmt) &&
!IsA(parsetree, DeallocateStmt))
{
instr_time start;
instr_time duration;
uint64 rows;
BufferUsage bufusage_start,
bufusage;
uint32 queryId;
bufusage_start = pgBufferUsage;
INSTR_TIME_SET_CURRENT(start);
nested_level++;
PG_TRY();
{
if (prev_ProcessUtility)
prev_ProcessUtility(parsetree, queryString,
context, params,
dest, completionTag);
else
standard_ProcessUtility(parsetree, queryString,
context, params,
dest, completionTag);
nested_level--;
}
PG_CATCH();
{
nested_level--;
PG_RE_THROW();
}
PG_END_TRY();
INSTR_TIME_SET_CURRENT(duration);
INSTR_TIME_SUBTRACT(duration, start);
/* parse command tag to retrieve the number of affected rows. */
if (completionTag &&
strncmp(completionTag, "COPY ", 5) == 0)
{
#ifdef HAVE_STRTOULL
rows = strtoull(completionTag + 5, NULL, 10);
#else
rows = strtoul(completionTag + 5, NULL, 10);
#endif
}
else
rows = 0;
/* calc differences of buffer counters. */
bufusage.shared_blks_hit =
pgBufferUsage.shared_blks_hit - bufusage_start.shared_blks_hit;
bufusage.shared_blks_read =
pgBufferUsage.shared_blks_read - bufusage_start.shared_blks_read;
bufusage.shared_blks_dirtied =
pgBufferUsage.shared_blks_dirtied - bufusage_start.shared_blks_dirtied;
bufusage.shared_blks_written =
pgBufferUsage.shared_blks_written - bufusage_start.shared_blks_written;
bufusage.local_blks_hit =
pgBufferUsage.local_blks_hit - bufusage_start.local_blks_hit;
bufusage.local_blks_read =
pgBufferUsage.local_blks_read - bufusage_start.local_blks_read;
bufusage.local_blks_dirtied =
pgBufferUsage.local_blks_dirtied - bufusage_start.local_blks_dirtied;
bufusage.local_blks_written =
pgBufferUsage.local_blks_written - bufusage_start.local_blks_written;
bufusage.temp_blks_read =
pgBufferUsage.temp_blks_read - bufusage_start.temp_blks_read;
bufusage.temp_blks_written =
pgBufferUsage.temp_blks_written - bufusage_start.temp_blks_written;
bufusage.blk_read_time = pgBufferUsage.blk_read_time;
INSTR_TIME_SUBTRACT(bufusage.blk_read_time, bufusage_start.blk_read_time);
bufusage.blk_write_time = pgBufferUsage.blk_write_time;
INSTR_TIME_SUBTRACT(bufusage.blk_write_time, bufusage_start.blk_write_time);
/* For utility statements, we just hash the query string directly */
queryId = pgss_hash_string(queryString);
pgss_store(queryString,
queryId,
INSTR_TIME_GET_MILLISEC(duration),
rows,
&bufusage,
NULL);
}
else
{
if (prev_ProcessUtility)
prev_ProcessUtility(parsetree, queryString,
context, params,
dest, completionTag);
else
standard_ProcessUtility(parsetree, queryString,
context, params,
dest, completionTag);
}
}
/*
* Calculate hash value for a key
*/
static uint32
pgss_hash_fn(const void *key, Size keysize)
{
const pgssHashKey *k = (const pgssHashKey *) key;
return hash_uint32((uint32) k->userid) ^
hash_uint32((uint32) k->dbid) ^
hash_uint32((uint32) k->queryid);
}
/*
* Compare two keys - zero means match
*/
static int
pgss_match_fn(const void *key1, const void *key2, Size keysize)
{
const pgssHashKey *k1 = (const pgssHashKey *) key1;
const pgssHashKey *k2 = (const pgssHashKey *) key2;
if (k1->userid == k2->userid &&
k1->dbid == k2->dbid &&
k1->queryid == k2->queryid)
return 0;
else
return 1;
}
/*
* Given an arbitrarily long query string, produce a hash for the purposes of
* identifying the query, without normalizing constants. Used when hashing
* utility statements.
*/
static uint32
pgss_hash_string(const char *str)
{
return hash_any((const unsigned char *) str, strlen(str));
}
/*
* 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 are ignored in this case.
*/
static void
pgss_store(const char *query, uint32 queryId,
double total_time, uint64 rows,
const BufferUsage *bufusage,
pgssJumbleState *jstate)
{
pgssHashKey key;
pgssEntry *entry;
char *norm_query = NULL;
int encoding = GetDatabaseEncoding();
int query_len;
Assert(query != NULL);
/* Safety check... */
if (!pgss || !pgss_hash)
return;
query_len = strlen(query);
/* Set up key for hashtable search */
key.userid = GetUserId();
key.dbid = MyDatabaseId;
key.queryid = queryId;
/* 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_len,
encoding);
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;
SpinLockAcquire(&e->mutex);
/* "Unstick" entry if it was previously sticky */
if (e->counters.calls == 0)
e->counters.usage = USAGE_INIT;
e->counters.calls += 1;
e->counters.total_time += 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.blk_read_time += INSTR_TIME_GET_MILLISEC(bufusage->blk_read_time);
e->counters.blk_write_time += INSTR_TIME_GET_MILLISEC(bufusage->blk_write_time);
e->counters.usage += USAGE_EXEC(total_time);
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 all statement statistics.
*/
Datum
pg_stat_statements_reset(PG_FUNCTION_ARGS)
{
if (!pgss || !pgss_hash)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("pg_stat_statements must be loaded via shared_preload_libraries")));
entry_reset();
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 19 /* 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_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;
TupleDesc tupdesc;
Tuplestorestate *tupstore;
MemoryContext per_query_ctx;
MemoryContext oldcontext;
Oid userid = GetUserId();
bool is_superuser = superuser();
char *qbuffer = NULL;
Size qbuffer_size = 0;
Size extent = 0;
int gc_count = 0;
HASH_SEQ_STATUS hash_seq;
pgssEntry *entry;
/* 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")));
/* check to see if caller supports us returning a tuplestore */
if (rsinfo == NULL || !IsA(rsinfo, ReturnSetInfo))
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("set-valued function called in context that cannot accept a set")));
if (!(rsinfo->allowedModes & SFRM_Materialize))
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("materialize mode required, but it is not " \
"allowed in this context")));
/* Switch into long-lived context to construct returned data structures */
per_query_ctx = rsinfo->econtext->ecxt_per_query_memory;
oldcontext = MemoryContextSwitchTo(per_query_ctx);
/* 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");
/*
* 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 (tupdesc->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;
default:
elog(ERROR, "incorrect number of output arguments");
}
tupstore = tuplestore_begin_heap(true, false, work_mem);
rsinfo->returnMode = SFRM_Materialize;
rsinfo->setResult = tupstore;
rsinfo->setDesc = tupdesc;
MemoryContextSwitchTo(oldcontext);
/*
* 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)
{
if (qbuffer)
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;
int64 queryid = entry->key.queryid;
memset(values, 0, sizeof(values));
memset(nulls, 0, sizeof(nulls));
values[i++] = ObjectIdGetDatum(entry->key.userid);
values[i++] = ObjectIdGetDatum(entry->key.dbid);
if (is_superuser || 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("<insufficient privilege>");
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;
SpinLockRelease(&e->mutex);
}
/* Skip entry if unexecuted (ie, it's a pending "sticky" entry) */
if (tmp.calls == 0)
continue;
values[i++] = Int64GetDatumFast(tmp.calls);
values[i++] = Float8GetDatumFast(tmp.total_time);
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.blk_read_time);
values[i++] = Float8GetDatumFast(tmp.blk_write_time);
}
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 :
-1 /* fail if you forget to update this assert */ ));
tuplestore_putvalues(tupstore, tupdesc, values, nulls);
}
/* clean up and return the tuplestore */
LWLockRelease(pgss->lock);
if (qbuffer)
free(qbuffer);
tuplestore_donestoring(tupstore);
}
/*
* 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;
}
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 totlen = 0;
/*
* 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.
*/
entries = palloc(hash_get_num_entries(pgss_hash) * sizeof(pgssEntry *));
i = 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 (entry->counters.calls == 0)
entry->counters.usage *= STICKY_DECREASE_FACTOR;
else
entry->counters.usage *= USAGE_DECREASE_FACTOR;
/* Accumulate total size, too. */
totlen += entry->query_len + 1;
}
qsort(entries, i, sizeof(pgssEntry *), entry_cmp);
if (i > 0)
{
/* Record the (approximate) median usage */
pgss->cur_median_usage = entries[i / 2]->counters.usage;
/* Record the mean query length */
pgss->mean_query_len = totlen / i;
}
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);
}
/*
* Given a null-terminated string, allocate a new entry in the external query
* text file and store the string there.
*
* Although we could compute the string length via strlen(), callers already
* have it handy, so we require them to pass it too.
*
* 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;
/* Now write the data into the successfully-reserved part of the file */
fd = OpenTransientFile(PGSS_TEXT_FILE, O_RDWR | O_CREAT | PG_BINARY,
S_IRUSR | S_IWUSR);
if (fd < 0)
goto error;
if (lseek(fd, off, SEEK_SET) != off)
goto error;
if (write(fd, query, query_len + 1) != 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 pg_stat_statement 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;
fd = OpenTransientFile(PGSS_TEXT_FILE, O_RDONLY | PG_BINARY, 0);
if (fd < 0)
{
if (errno != ENOENT)
ereport(LOG,
(errcode_for_file_access(),
errmsg("could not read pg_stat_statement 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 pg_stat_statement 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 <= MaxAllocSize)
buf = (char *) malloc(stat.st_size);
else
buf = NULL;
if (buf == NULL)
{
ereport(LOG,
(errcode(ERRCODE_OUT_OF_MEMORY),
errmsg("out of memory")));
CloseTransientFile(fd);
return NULL;
}
/*
* OK, slurp in the file. 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, stat.st_size) != stat.st_size)
{
if (errno)
ereport(LOG,
(errcode_for_file_access(),
errmsg("could not read pg_stat_statement file \"%s\": %m",
PGSS_TEXT_FILE)));
free(buf);
CloseTransientFile(fd);
return NULL;
}
CloseTransientFile(fd);
*buffer_size = stat.st_size;
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 */
if (extent < 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 (extent < 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.
*/
static void
gc_qtexts(void)
{
char *qbuffer;
Size qbuffer_size;
FILE *qfile;
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) just
* skip the garbage collection.
*/
qbuffer = qtext_load_file(&qbuffer_size);
if (qbuffer == NULL)
return;
/*
* 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 pg_stat_statement 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;
continue;
}
if (fwrite(qry, 1, query_len + 1, qfile) != query_len + 1)
{
ereport(LOG,
(errcode_for_file_access(),
errmsg("could not write pg_stat_statement 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 pg_stat_statement file \"%s\": %m",
PGSS_TEXT_FILE)));
if (FreeFile(qfile))
{
ereport(LOG,
(errcode_for_file_access(),
errmsg("could not write pg_stat_statement 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);
if (qbuffer)
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;
}
/* Seems like a good idea to bump the GC count even though we failed */
record_gc_qtexts();
}
/*
* Release all entries.
*/
static void
entry_reset(void)
{
HASH_SEQ_STATUS hash_seq;
pgssEntry *entry;
FILE *qfile;
LWLockAcquire(pgss->lock, LW_EXCLUSIVE);
hash_seq_init(&hash_seq, pgss_hash);
while ((entry = hash_seq_search(&hash_seq)) != NULL)
{
hash_search(pgss_hash, &entry->key, HASH_REMOVE, NULL);
}
/*
* 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 pg_stat_statement 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 pg_stat_statement 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();
LWLockRelease(pgss->lock);
}
/*
* AppendJumble: Append a value that is substantive in a given query to
* the current jumble.
*/
static void
AppendJumble(pgssJumbleState *jstate, const unsigned char *item, Size size)
{
unsigned char *jumble = jstate->jumble;
Size jumble_len = jstate->jumble_len;
/*
* Whenever the jumble buffer is full, we hash the current contents and
* reset the buffer to contain just that hash value, thus relying on the
* hash to summarize everything so far.
*/
while (size > 0)
{
Size part_size;
if (jumble_len >= JUMBLE_SIZE)
{
uint32 start_hash = hash_any(jumble, JUMBLE_SIZE);
memcpy(jumble, &start_hash, sizeof(start_hash));
jumble_len = sizeof(start_hash);
}
part_size = Min(size, JUMBLE_SIZE - jumble_len);
memcpy(jumble + jumble_len, item, part_size);
jumble_len += part_size;
item += part_size;
size -= part_size;
}
jstate->jumble_len = jumble_len;
}
/*
* Wrappers around AppendJumble to encapsulate details of serialization
* of individual local variable elements.
*/
#define APP_JUMB(item) \
AppendJumble(jstate, (const unsigned char *) &(item), sizeof(item))
#define APP_JUMB_STRING(str) \
AppendJumble(jstate, (const unsigned char *) (str), strlen(str) + 1)
/*
* JumbleQuery: Selectively serialize the query tree, appending significant
* data to the "query jumble" while ignoring nonsignificant data.
*
* Rule of thumb for what to include is that we should ignore anything not
* semantically significant (such as alias names) as well as anything that can
* be deduced from child nodes (else we'd just be double-hashing that piece
* of information).
*/
static void
JumbleQuery(pgssJumbleState *jstate, Query *query)
{
Assert(IsA(query, Query));
Assert(query->utilityStmt == NULL);
APP_JUMB(query->commandType);
/* resultRelation is usually predictable from commandType */
JumbleExpr(jstate, (Node *) query->cteList);
JumbleRangeTable(jstate, query->rtable);
JumbleExpr(jstate, (Node *) query->jointree);
JumbleExpr(jstate, (Node *) query->targetList);
JumbleExpr(jstate, (Node *) query->returningList);
JumbleExpr(jstate, (Node *) query->groupClause);
JumbleExpr(jstate, query->havingQual);
JumbleExpr(jstate, (Node *) query->windowClause);
JumbleExpr(jstate, (Node *) query->distinctClause);
JumbleExpr(jstate, (Node *) query->sortClause);
JumbleExpr(jstate, query->limitOffset);
JumbleExpr(jstate, query->limitCount);
/* we ignore rowMarks */
JumbleExpr(jstate, query->setOperations);
}
/*
* Jumble a range table
*/
static void
JumbleRangeTable(pgssJumbleState *jstate, List *rtable)
{
ListCell *lc;
foreach(lc, rtable)
{
RangeTblEntry *rte = (RangeTblEntry *) lfirst(lc);
Assert(IsA(rte, RangeTblEntry));
APP_JUMB(rte->rtekind);
switch (rte->rtekind)
{
case RTE_RELATION:
APP_JUMB(rte->relid);
break;
case RTE_SUBQUERY:
JumbleQuery(jstate, rte->subquery);
break;
case RTE_JOIN:
APP_JUMB(rte->jointype);
break;
case RTE_FUNCTION:
JumbleExpr(jstate, (Node *) rte->functions);
break;
case RTE_VALUES:
JumbleExpr(jstate, (Node *) rte->values_lists);
break;
case RTE_CTE:
/*
* Depending on the CTE name here isn't ideal, but it's the
* only info we have to identify the referenced WITH item.
*/
APP_JUMB_STRING(rte->ctename);
APP_JUMB(rte->ctelevelsup);
break;
default:
elog(ERROR, "unrecognized RTE kind: %d", (int) rte->rtekind);
break;
}
}
}
/*
* Jumble an expression tree
*
* In general this function should handle all the same node types that
* expression_tree_walker() does, and therefore it's coded to be as parallel
* to that function as possible. However, since we are only invoked on
* queries immediately post-parse-analysis, we need not handle node types
* that only appear in planning.
*
* Note: the reason we don't simply use expression_tree_walker() is that the
* point of that function is to support tree walkers that don't care about
* most tree node types, but here we care about all types. We should complain
* about any unrecognized node type.
*/
static void
JumbleExpr(pgssJumbleState *jstate, Node *node)
{
ListCell *temp;
if (node == NULL)
return;
/* Guard against stack overflow due to overly complex expressions */
check_stack_depth();
/*
* We always emit the node's NodeTag, then any additional fields that are
* considered significant, and then we recurse to any child nodes.
*/
APP_JUMB(node->type);
switch (nodeTag(node))
{
case T_Var:
{
Var *var = (Var *) node;
APP_JUMB(var->varno);
APP_JUMB(var->varattno);
APP_JUMB(var->varlevelsup);
}
break;
case T_Const:
{
Const *c = (Const *) node;
/* We jumble only the constant's type, not its value */
APP_JUMB(c->consttype);
/* Also, record its parse location for query normalization */
RecordConstLocation(jstate, c->location);
}
break;
case T_Param:
{
Param *p = (Param *) node;
APP_JUMB(p->paramkind);
APP_JUMB(p->paramid);
APP_JUMB(p->paramtype);
}
break;
case T_Aggref:
{
Aggref *expr = (Aggref *) node;
APP_JUMB(expr->aggfnoid);
JumbleExpr(jstate, (Node *) expr->aggdirectargs);
JumbleExpr(jstate, (Node *) expr->args);
JumbleExpr(jstate, (Node *) expr->aggorder);
JumbleExpr(jstate, (Node *) expr->aggdistinct);
JumbleExpr(jstate, (Node *) expr->aggfilter);
}
break;
case T_WindowFunc:
{
WindowFunc *expr = (WindowFunc *) node;
APP_JUMB(expr->winfnoid);
APP_JUMB(expr->winref);
JumbleExpr(jstate, (Node *) expr->args);
JumbleExpr(jstate, (Node *) expr->aggfilter);
}
break;
case T_ArrayRef:
{
ArrayRef *aref = (ArrayRef *) node;
JumbleExpr(jstate, (Node *) aref->refupperindexpr);
JumbleExpr(jstate, (Node *) aref->reflowerindexpr);
JumbleExpr(jstate, (Node *) aref->refexpr);
JumbleExpr(jstate, (Node *) aref->refassgnexpr);
}
break;
case T_FuncExpr:
{
FuncExpr *expr = (FuncExpr *) node;
APP_JUMB(expr->funcid);
JumbleExpr(jstate, (Node *) expr->args);
}
break;
case T_NamedArgExpr:
{
NamedArgExpr *nae = (NamedArgExpr *) node;
APP_JUMB(nae->argnumber);
JumbleExpr(jstate, (Node *) nae->arg);
}
break;
case T_OpExpr:
case T_DistinctExpr: /* struct-equivalent to OpExpr */
case T_NullIfExpr: /* struct-equivalent to OpExpr */
{
OpExpr *expr = (OpExpr *) node;
APP_JUMB(expr->opno);
JumbleExpr(jstate, (Node *) expr->args);
}
break;
case T_ScalarArrayOpExpr:
{
ScalarArrayOpExpr *expr = (ScalarArrayOpExpr *) node;
APP_JUMB(expr->opno);
APP_JUMB(expr->useOr);
JumbleExpr(jstate, (Node *) expr->args);
}
break;
case T_BoolExpr:
{
BoolExpr *expr = (BoolExpr *) node;
APP_JUMB(expr->boolop);
JumbleExpr(jstate, (Node *) expr->args);
}
break;
case T_SubLink:
{
SubLink *sublink = (SubLink *) node;
APP_JUMB(sublink->subLinkType);
APP_JUMB(sublink->subLinkId);
JumbleExpr(jstate, (Node *) sublink->testexpr);
JumbleQuery(jstate, (Query *) sublink->subselect);
}
break;
case T_FieldSelect:
{
FieldSelect *fs = (FieldSelect *) node;
APP_JUMB(fs->fieldnum);
JumbleExpr(jstate, (Node *) fs->arg);
}
break;
case T_FieldStore:
{
FieldStore *fstore = (FieldStore *) node;
JumbleExpr(jstate, (Node *) fstore->arg);
JumbleExpr(jstate, (Node *) fstore->newvals);
}
break;
case T_RelabelType:
{
RelabelType *rt = (RelabelType *) node;
APP_JUMB(rt->resulttype);
JumbleExpr(jstate, (Node *) rt->arg);
}
break;
case T_CoerceViaIO:
{
CoerceViaIO *cio = (CoerceViaIO *) node;
APP_JUMB(cio->resulttype);
JumbleExpr(jstate, (Node *) cio->arg);
}
break;
case T_ArrayCoerceExpr:
{
ArrayCoerceExpr *acexpr = (ArrayCoerceExpr *) node;
APP_JUMB(acexpr->resulttype);
JumbleExpr(jstate, (Node *) acexpr->arg);
}
break;
case T_ConvertRowtypeExpr:
{
ConvertRowtypeExpr *crexpr = (ConvertRowtypeExpr *) node;
APP_JUMB(crexpr->resulttype);
JumbleExpr(jstate, (Node *) crexpr->arg);
}
break;
case T_CollateExpr:
{
CollateExpr *ce = (CollateExpr *) node;
APP_JUMB(ce->collOid);
JumbleExpr(jstate, (Node *) ce->arg);
}
break;
case T_CaseExpr:
{
CaseExpr *caseexpr = (CaseExpr *) node;
JumbleExpr(jstate, (Node *) caseexpr->arg);
foreach(temp, caseexpr->args)
{
CaseWhen *when = (CaseWhen *) lfirst(temp);
Assert(IsA(when, CaseWhen));
JumbleExpr(jstate, (Node *) when->expr);
JumbleExpr(jstate, (Node *) when->result);
}
JumbleExpr(jstate, (Node *) caseexpr->defresult);
}
break;
case T_CaseTestExpr:
{
CaseTestExpr *ct = (CaseTestExpr *) node;
APP_JUMB(ct->typeId);
}
break;
case T_ArrayExpr:
JumbleExpr(jstate, (Node *) ((ArrayExpr *) node)->elements);
break;
case T_RowExpr:
JumbleExpr(jstate, (Node *) ((RowExpr *) node)->args);
break;
case T_RowCompareExpr:
{
RowCompareExpr *rcexpr = (RowCompareExpr *) node;
APP_JUMB(rcexpr->rctype);
JumbleExpr(jstate, (Node *) rcexpr->largs);
JumbleExpr(jstate, (Node *) rcexpr->rargs);
}
break;
case T_CoalesceExpr:
JumbleExpr(jstate, (Node *) ((CoalesceExpr *) node)->args);
break;
case T_MinMaxExpr:
{
MinMaxExpr *mmexpr = (MinMaxExpr *) node;
APP_JUMB(mmexpr->op);
JumbleExpr(jstate, (Node *) mmexpr->args);
}
break;
case T_XmlExpr:
{
XmlExpr *xexpr = (XmlExpr *) node;
APP_JUMB(xexpr->op);
JumbleExpr(jstate, (Node *) xexpr->named_args);
JumbleExpr(jstate, (Node *) xexpr->args);
}
break;
case T_NullTest:
{
NullTest *nt = (NullTest *) node;
APP_JUMB(nt->nulltesttype);
JumbleExpr(jstate, (Node *) nt->arg);
}
break;
case T_BooleanTest:
{
BooleanTest *bt = (BooleanTest *) node;
APP_JUMB(bt->booltesttype);
JumbleExpr(jstate, (Node *) bt->arg);
}
break;
case T_CoerceToDomain:
{
CoerceToDomain *cd = (CoerceToDomain *) node;
APP_JUMB(cd->resulttype);
JumbleExpr(jstate, (Node *) cd->arg);
}
break;
case T_CoerceToDomainValue:
{
CoerceToDomainValue *cdv = (CoerceToDomainValue *) node;
APP_JUMB(cdv->typeId);
}
break;
case T_SetToDefault:
{
SetToDefault *sd = (SetToDefault *) node;
APP_JUMB(sd->typeId);
}
break;
case T_CurrentOfExpr:
{
CurrentOfExpr *ce = (CurrentOfExpr *) node;
APP_JUMB(ce->cvarno);
if (ce->cursor_name)
APP_JUMB_STRING(ce->cursor_name);
APP_JUMB(ce->cursor_param);
}
break;
case T_TargetEntry:
{
TargetEntry *tle = (TargetEntry *) node;
APP_JUMB(tle->resno);
APP_JUMB(tle->ressortgroupref);
JumbleExpr(jstate, (Node *) tle->expr);
}
break;
case T_RangeTblRef:
{
RangeTblRef *rtr = (RangeTblRef *) node;
APP_JUMB(rtr->rtindex);
}
break;
case T_JoinExpr:
{
JoinExpr *join = (JoinExpr *) node;
APP_JUMB(join->jointype);
APP_JUMB(join->isNatural);
APP_JUMB(join->rtindex);
JumbleExpr(jstate, join->larg);
JumbleExpr(jstate, join->rarg);
JumbleExpr(jstate, join->quals);
}
break;
case T_FromExpr:
{
FromExpr *from = (FromExpr *) node;
JumbleExpr(jstate, (Node *) from->fromlist);
JumbleExpr(jstate, from->quals);
}
break;
case T_List:
foreach(temp, (List *) node)
{
JumbleExpr(jstate, (Node *) lfirst(temp));
}
break;
case T_SortGroupClause:
{
SortGroupClause *sgc = (SortGroupClause *) node;
APP_JUMB(sgc->tleSortGroupRef);
APP_JUMB(sgc->eqop);
APP_JUMB(sgc->sortop);
APP_JUMB(sgc->nulls_first);
}
break;
case T_WindowClause:
{
WindowClause *wc = (WindowClause *) node;
APP_JUMB(wc->winref);
APP_JUMB(wc->frameOptions);
JumbleExpr(jstate, (Node *) wc->partitionClause);
JumbleExpr(jstate, (Node *) wc->orderClause);
JumbleExpr(jstate, wc->startOffset);
JumbleExpr(jstate, wc->endOffset);
}
break;
case T_CommonTableExpr:
{
CommonTableExpr *cte = (CommonTableExpr *) node;
/* we store the string name because RTE_CTE RTEs need it */
APP_JUMB_STRING(cte->ctename);
JumbleQuery(jstate, (Query *) cte->ctequery);
}
break;
case T_SetOperationStmt:
{
SetOperationStmt *setop = (SetOperationStmt *) node;
APP_JUMB(setop->op);
APP_JUMB(setop->all);
JumbleExpr(jstate, setop->larg);
JumbleExpr(jstate, setop->rarg);
}
break;
case T_RangeTblFunction:
{
RangeTblFunction *rtfunc = (RangeTblFunction *) node;
JumbleExpr(jstate, rtfunc->funcexpr);
}
break;
default:
/* Only a warning, since we can stumble along anyway */
elog(WARNING, "unrecognized node type: %d",
(int) nodeTag(node));
break;
}
}
/*
* Record location of constant within query string of query tree
* that is currently being walked.
*/
static void
RecordConstLocation(pgssJumbleState *jstate, int location)
{
/* -1 indicates unknown or undefined location */
if (location >= 0)
{
/* enlarge array if needed */
if (jstate->clocations_count >= jstate->clocations_buf_size)
{
jstate->clocations_buf_size *= 2;
jstate->clocations = (pgssLocationLen *)
repalloc(jstate->clocations,
jstate->clocations_buf_size *
sizeof(pgssLocationLen));
}
jstate->clocations[jstate->clocations_count].location = location;
/* initialize lengths to -1 to simplify fill_in_constant_lengths */
jstate->clocations[jstate->clocations_count].length = -1;
jstate->clocations_count++;
}
}
/*
* 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.
*
* *query_len_p contains the input string length, and is updated with
* the result string length (which cannot be longer) on exit.
*
* Returns a palloc'd string.
*/
static char *
generate_normalized_query(pgssJumbleState *jstate, const char *query,
int *query_len_p, int encoding)
{
char *norm_query;
int query_len = *query_len_p;
int i,
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);
/* Allocate result buffer */
norm_query = palloc(query_len + 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;
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 '?' in place of the constant token */
norm_query[n_quer_loc++] = '?';
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 <= query_len);
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.)
*
* 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(pgssJumbleState *jstate, const char *query)
{
pgssLocationLen *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(pgssLocationLen), comp_location);
locs = jstate->clocations;
/* initialize the flex scanner --- should match raw_parser() */
yyscanner = scanner_init(query,
&yyextra,
ScanKeywords,
NumScanKeywords);
/* Search for each constant, in sequence */
for (i = 0; i < jstate->clocations_count; i++)
{
int loc = locs[i].location;
int tok;
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 pgssLocationLen structs by location
*/
static int
comp_location(const void *a, const void *b)
{
int l = ((const pgssLocationLen *) a)->location;
int r = ((const pgssLocationLen *) b)->location;
if (l < r)
return -1;
else if (l > r)
return +1;
else
return 0;
}
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