Store denormalized query only under certain constraints
This commit introduces a little optimization along with a feature, it stores the query in denormalized form only under the circumstances below: - The psgm_normalized_query GUC is disabled (off). - The query is seem for the first time, or the query total execution time exceeds the mean execution time calculated for the previous queries. Having the query which took most execution time along with it's arguments could help users in further investigating performance issues.pull/481/head
Diego Fronza
parent
a1f452c18c
commit
2031e89b62
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@ -208,13 +208,8 @@ static void pgsm_add_to_list(pgsmEntry *entry, char *query_text, int query_len);
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static pgsmEntry *pgsm_get_entry_for_query(uint64 queryid, PlanInfo *plan_info, const char *query_text, int query_len, bool create);
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static uint64 get_pgsm_query_id_hash(const char *norm_query, int len);
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/*
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* extract parameter value (Datum) from plist->params[idx], cast it to string then
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* append the resulting string to the buffer.
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*/
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static void get_param_value(const ParamListInfo plist, int idx, StringInfoData *buffer);
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/* denormalize the query, replace placeholders with actual values */
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static StringInfoData get_denormalized_query(const ParamListInfo paramlist, const char *query_text);
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static void pgsm_cleanup_callback(void *arg);
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@ -243,7 +238,13 @@ static void pgsm_update_entry(pgsmEntry *entry,
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const struct JitInstrumentation *jitusage,
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bool reset,
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pgsmStoreKind kind);
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static void pgsm_store(pgsmEntry *entry);
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static void pgsm_store_ex(pgsmEntry * entry, ParamListInfo params);
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/* Stores query entry in normalized form */
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static inline void pgsm_store(pgsmEntry * entry)
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{
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pgsm_store_ex(entry, NULL);
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}
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static void pg_stat_monitor_internal(FunctionCallInfo fcinfo,
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pgsmVersion api_version,
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@ -703,7 +704,6 @@ pgsm_ExecutorEnd(QueryDesc *queryDesc)
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PlanInfo plan_info;
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PlanInfo *plan_ptr = NULL;
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pgsmEntry *entry = NULL;
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StringInfoData query_info;
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MemoryContext oldctx;
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/* Extract the plan information in case of SELECT statement */
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@ -763,13 +763,6 @@ pgsm_ExecutorEnd(QueryDesc *queryDesc)
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sys_info.stime = time_diff(rusage_end.ru_stime, rusage_start.ru_stime);
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}
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if (!pgsm_normalized_query && queryDesc->params) {
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query_info = get_denormalized_query(queryDesc->params, queryDesc->sourceText);
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oldctx = MemoryContextSwitchTo(GetPgsmMemoryContext());
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entry->query_text.query_pointer = pnstrdup(query_info.data, query_info.len);
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MemoryContextSwitchTo(oldctx);
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}
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pgsm_update_entry(entry, /* entry */
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NULL, /* query */
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NULL, /* comments */
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@ -794,7 +787,7 @@ pgsm_ExecutorEnd(QueryDesc *queryDesc)
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false, /* reset */
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PGSM_EXEC); /* kind */
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pgsm_store(entry);
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pgsm_store_ex(entry, queryDesc->params);
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}
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if (prev_ExecutorEnd)
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@ -1880,7 +1873,6 @@ pgsm_create_hash_entry(uint64 bucket_id, uint64 queryid, PlanInfo *plan_info)
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return entry;
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}
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/*
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* Store some statistics for a statement.
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*
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@ -1890,9 +1882,14 @@ pgsm_create_hash_entry(uint64 bucket_id, uint64 queryid, PlanInfo *plan_info)
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* If jstate is not NULL then we're trying to create an entry for which
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* we have no statistics as yet; we just want to record the normalized
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* query string. total_time, rows, bufusage are ignored in this case.
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*
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* If params argument is not null and pgsm_normalized_query is off then we
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* denormalize the query using it's actual arguments found in params.
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* The denormalization is done during the first time the query is
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* inserted or if the time to execute the query exceeds the average
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* time computed for the same query.
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*/
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static void
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pgsm_store(pgsmEntry *entry)
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void pgsm_store_ex(pgsmEntry *entry, ParamListInfo params)
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{
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pgsmEntry *shared_hash_entry;
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pgsmSharedState *pgsm;
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@ -1907,6 +1904,7 @@ pgsm_store(pgsmEntry *entry)
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JitInstrumentation jitusage;
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char comments[COMMENTS_LEN] = {0};
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int comments_len;
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StringInfoData query_info;
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/* Safety check... */
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if (!IsSystemInitialized())
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@ -1995,6 +1993,13 @@ pgsm_store(pgsmEntry *entry)
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dsa_area *query_dsa_area;
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char *query_buff;
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/* Denormalize the query if normalization is off */
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if (!pgsm_normalized_query && params != NULL) {
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query_info = get_denormalized_query(params, query);
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query = query_info.data;
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query_len = query_info.len;
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}
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/* New query, truncate length if necessary. */
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if (query_len > pgsm_query_max_len)
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query_len = pgsm_query_max_len;
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@ -2083,6 +2088,43 @@ pgsm_store(pgsmEntry *entry)
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snprintf(shared_hash_entry->datname, sizeof(shared_hash_entry->datname), "%s", entry->datname);
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snprintf(shared_hash_entry->username, sizeof(shared_hash_entry->username), "%s", entry->username);
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}
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/* Entry already exists, if query normalization is disabled and
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* the query execution time exceeds the mean time for this query,
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* then we denormalize the query so users can inspect which arguments
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* caused the query to take more time to execute */
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else if (
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!pgsm_normalized_query &&
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params != NULL &&
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entry->counters.time.total_time > shared_hash_entry->counters.time.mean_time
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){
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dsa_pointer dsa_query_pointer;
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dsa_area *query_dsa_area;
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char *query_buff;
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query_info = get_denormalized_query(params, query);
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query = query_info.data;
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query_len = query_info.len;
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/* truncate length if necessary. */
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if (query_len > pgsm_query_max_len)
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query_len = pgsm_query_max_len;
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/* Save the query text in raw dsa area */
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query_dsa_area = get_dsa_area_for_query_text();
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dsa_query_pointer = dsa_allocate_extended(query_dsa_area, query_len + 1, DSA_ALLOC_NO_OOM | DSA_ALLOC_ZERO);
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if (DsaPointerIsValid(dsa_query_pointer))
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{
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/* Get the memory address from DSA pointer and copy the query text to it. */
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query_buff = dsa_get_address(query_dsa_area, dsa_query_pointer);
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memcpy(query_buff, query, query_len);
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/* release previous query from shared memory */
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if (DsaPointerIsValid(shared_hash_entry->query_text.query_pos))
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dsa_free(query_dsa_area, shared_hash_entry->query_text.query_pos);
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shared_hash_entry->query_text.query_pos = dsa_query_pointer;
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}
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}
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pgsm_update_entry(shared_hash_entry, /* entry */
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query, /* query */
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@ -4038,6 +4080,10 @@ get_query_id(JumbleState *jstate, Query *query)
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}
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#endif
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/*
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* extract parameter value (Datum) from plist->params[idx], cast it to string then
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* append the resulting string to the buffer.
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*/
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void
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get_param_value(const ParamListInfo plist, int idx, StringInfoData *buffer)
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{
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@ -4061,6 +4107,7 @@ get_param_value(const ParamListInfo plist, int idx, StringInfoData *buffer)
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appendStringInfo(buffer, "%s", pstring);
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}
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/* denormalize the query, replace placeholders with actual values */
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StringInfoData
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get_denormalized_query(const ParamListInfo paramlist, const char *query_text)
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{
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