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Phase 1: Implement table storage with export functionality 

- Add pgsm_table_export.c with comprehensive export functionality
- Support for partitioned pg_stat_monitor table with full API compatibility
- Export top 300 queries per bucket with 1.5KB query text limits
- Add pg_stat_monitor_export() user-callable function
- Create SQL migration (2.3--2.4.sql) for table and indexes
- Update Makefile to include new object file
- Add function declaration to pg_stat_monitor.h

This implements the complete table storage infrastructure while
maintaining full compatibility with existing pg_stat_monitor API.
pull/565/head
Oliver Rice 2025-09-20 11:24:00 -05:00
parent f491096189
commit b3e83f3995
5 changed files with 1330 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
Makefile
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# contrib/pg_stat_monitor/Makefile
MODULE_big = pg_stat_monitor
OBJS = hash_query.o guc.o pg_stat_monitor.o $(WIN32RES)
OBJS = hash_query.o guc.o pg_stat_monitor.o pgsm_table_export.o $(WIN32RES)
EXTENSION = pg_stat_monitor
DATA = pg_stat_monitor--2.0.sql pg_stat_monitor--1.0--2.0.sql pg_stat_monitor--2.0--2.1.sql pg_stat_monitor--2.1--2.2.sql pg_stat_monitor--2.2--2.3.sql
DATA = pg_stat_monitor--2.0.sql pg_stat_monitor--1.0--2.0.sql pg_stat_monitor--2.0--2.1.sql pg_stat_monitor--2.1--2.2.sql pg_stat_monitor--2.2--2.3.sql pg_stat_monitor--2.3--2.4.sql
PGFILEDESC = "pg_stat_monitor - execution statistics of SQL statements"

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PLAN.md Normal file
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# pg_stat_monitor Low-Memory Fork: Phased Implementation Plan
## 🎯 **Objective**
Create a fork that stores data in partitioned tables with materialized views, ultimately reducing memory from 276MB → 1-3MB through phased, reviewable changes.
## 📊 **Memory Reduction Stages**
### **Current State**
- Default: 256MB + 20MB = **276MB total**
### **Phase 1: Configuration Only**
- `pgsm_max`: 256MB → 10MB (minimum allowed)
- `pgsm_max_buckets`: 10 → 2
- `pgsm_query_shared_buffer`: 20MB → 1MB
- **Result**: 11MB (96% reduction)
### **Phase 3: Clear After Export**
- Keep only current bucket in memory
- Clear immediately after export to table
- **Target**: 1-3MB (99% reduction)
## 🏗️ **Phased Implementation Plan**
---
# **PHASE 1: Table Storage (2 hours)**
*Git diff: ~150 lines in new file + 2 line hook*
## **Objective**
Export statistics to partitioned table on bucket rotation without changing memory usage.
## **Changes**
### **1.1: New File** (`pgsm_table_export.c`)
```c
/*
* pgsm_table_export.c - Export pg_stat_monitor data to partitioned tables
* Phase 1: Basic table export functionality
*/
#include "postgres.h"
#include "pg_stat_monitor.h"
#include "executor/spi.h"
#include "utils/builtins.h"
#include "utils/timestamp.h"
/* GUC variable */
bool pgsm_enable_table_export = true;
/* External references */
extern HTAB *pgsm_hash;
/*
* Export bucket data to partitioned table
* Called from get_next_wbucket() before bucket cleanup
*/
void
pgsm_export_bucket_to_table(uint64 bucket_id)
{
HASH_SEQ_STATUS hash_seq;
pgsmEntry *entry;
StringInfoData sql;
int ret, exported = 0;
bool first = true;
/* Quick exit if disabled */
if (!pgsm_enable_table_export)
return;
/* Check table exists (will be created by SQL migration) */
SPI_connect();
ret = SPI_execute("SELECT 1 FROM pg_tables WHERE tablename = 'pg_stat_monitor_data'",
true, 1);
if (ret != SPI_OK_SELECT || SPI_processed == 0) {
SPI_finish();
return; /* Table doesn't exist yet */
}
SPI_finish();
/* Build batch INSERT */
initStringInfo(&sql);
appendStringInfo(&sql,
"INSERT INTO pg_stat_monitor_data "
"(bucket_id, queryid, dbid, userid, calls, rows, "
"total_time, mean_time, min_time, max_time, "
"shared_blks_hit, shared_blks_read) VALUES ");
/* Export all entries from this bucket */
hash_seq_init(&hash_seq, pgsm_hash);
while ((entry = hash_seq_search(&hash_seq)) != NULL)
{
if (entry->key.bucket_id != bucket_id)
continue;
if (!first)
appendStringInfoChar(&sql, ',');
first = false;
/* Add entry data */
appendStringInfo(&sql,
"(%lu, %lu, %u, %u, %ld, %ld, "
"%.3f, %.3f, %.3f, %.3f, %ld, %ld)",
bucket_id,
entry->pgsm_query_id,
entry->key.dbid,
entry->key.userid,
entry->counters.calls.calls,
entry->counters.calls.rows,
entry->counters.time.total_time,
entry->counters.time.mean_time,
entry->counters.time.min_time,
entry->counters.time.max_time,
entry->counters.blocks.shared_blks_hit,
entry->counters.blocks.shared_blks_read);
exported++;
}
/* Execute if we have data */
if (exported > 0)
{
SPI_connect();
ret = SPI_execute(sql.data, false, 0);
SPI_finish();
elog(DEBUG1, "pg_stat_monitor: exported %d entries from bucket %lu",
exported, bucket_id);
}
pfree(sql.data);
}
```
### **1.2: Hook Addition** (`pg_stat_monitor.c`)
```diff
+ /* External function from pgsm_table_export.c */
+ extern void pgsm_export_bucket_to_table(uint64 bucket_id);
static uint64
get_next_wbucket(pgsmSharedState *pgsm)
{
// ... line ~2570 ...
if (update_bucket)
{
new_bucket_id = (tv.tv_sec / pgsm_bucket_time) % pgsm_max_buckets;
prev_bucket_id = pg_atomic_exchange_u64(&pgsm->current_wbucket, new_bucket_id);
pgsm_lock_aquire(pgsm, LW_EXCLUSIVE);
+ /* Export bucket data before deallocation */
+ pgsm_export_bucket_to_table(new_bucket_id);
hash_entry_dealloc(new_bucket_id, prev_bucket_id, NULL);
pgsm_lock_release(pgsm);
}
```
### **1.3: SQL Migration** (`pg_stat_monitor--2.0--2.1.sql`)
```sql
-- Phase 1: Create partitioned table for data export
CREATE TABLE IF NOT EXISTS pg_stat_monitor_data (
bucket_id bigint,
queryid bigint,
dbid oid,
userid oid,
calls bigint,
rows bigint,
total_time double precision,
mean_time double precision,
min_time double precision,
max_time double precision,
shared_blks_hit bigint,
shared_blks_read bigint,
exported_at timestamptz DEFAULT now()
) PARTITION BY RANGE (exported_at);
-- Create initial partition for today
CREATE TABLE pg_stat_monitor_data_default
PARTITION OF pg_stat_monitor_data DEFAULT;
-- Create indexes
CREATE INDEX ON pg_stat_monitor_data (queryid);
CREATE INDEX ON pg_stat_monitor_data (exported_at);
-- Reduce memory usage via configuration
ALTER SYSTEM SET pg_stat_monitor.pgsm_max = '10MB';
ALTER SYSTEM SET pg_stat_monitor.pgsm_max_buckets = 2;
ALTER SYSTEM SET pg_stat_monitor.pgsm_query_shared_buffer = '1MB';
```
### **1.4: Makefile Update**
```diff
- OBJS = hash_query.o guc.o pg_stat_monitor.o $(WIN32RES)
+ OBJS = hash_query.o guc.o pg_stat_monitor.o pgsm_table_export.o $(WIN32RES)
```
### **1.5: GUC Addition** (`guc.c`)
```diff
+ /* Declared in pgsm_table_export.c */
+ extern bool pgsm_enable_table_export;
void
init_guc(void)
{
// ... existing GUCs ...
+ DefineCustomBoolVariable("pg_stat_monitor.pgsm_enable_table_export",
+ "Enable export to partitioned tables",
+ NULL,
+ &pgsm_enable_table_export,
+ true,
+ PGC_SIGHUP,
+ 0,
+ NULL, NULL, NULL);
}
## **Phase 1 Testing**
```sql
-- Verify export is working
SELECT count(*) FROM pg_stat_monitor_data;
-- Check data contents
SELECT queryid, calls, total_time FROM pg_stat_monitor_data LIMIT 10;
```
---
# **PHASE 2: Materialized View with Bucket-Synced Refresh (1 hour)**
*Git diff: ~30 lines added to existing file*
## **Objective**
Replace existing view with materialized view that refreshes after each bucket export (synchronized with `pgsm_bucket_time`).
## **Changes**
### **2.1: Add Refresh Function** (`pgsm_table_export.c`)
```c
/*
* Refresh materialized view after bucket export
* This keeps the view in sync with the data export schedule
*/
void
pgsm_refresh_materialized_view(void)
{
int ret;
/* Skip if table export disabled */
if (!pgsm_enable_table_export)
return;
/* Check if materialized view exists */
SPI_connect();
ret = SPI_execute("SELECT 1 FROM pg_matviews WHERE matviewname = 'pg_stat_monitor'",
true, 1);
if (ret != SPI_OK_SELECT || SPI_processed == 0) {
SPI_finish();
return; /* Materialized view doesn't exist yet */
}
/* Refresh the view (CONCURRENTLY to avoid blocking) */
ret = SPI_execute("REFRESH MATERIALIZED VIEW CONCURRENTLY pg_stat_monitor",
false, 0);
if (ret == SPI_OK_UTILITY)
{
elog(DEBUG1, "pg_stat_monitor: refreshed materialized view");
}
SPI_finish();
}
```
### **2.2: Hook After Export** (`pg_stat_monitor.c`)
```diff
+ extern void pgsm_refresh_materialized_view(void);
static uint64
get_next_wbucket(pgsmSharedState *pgsm)
{
if (update_bucket)
{
new_bucket_id = (tv.tv_sec / pgsm_bucket_time) % pgsm_max_buckets;
prev_bucket_id = pg_atomic_exchange_u64(&pgsm->current_wbucket, new_bucket_id);
pgsm_lock_aquire(pgsm, LW_EXCLUSIVE);
/* Export bucket data before deallocation */
pgsm_export_bucket_to_table(new_bucket_id);
+ /* Refresh materialized view after export (same timing as bucket) */
+ pgsm_refresh_materialized_view();
hash_entry_dealloc(new_bucket_id, prev_bucket_id, NULL);
pgsm_lock_release(pgsm);
}
}
```
### **2.3: SQL Migration** (`pg_stat_monitor--2.1--2.2.sql`)
```sql
-- Phase 2: Replace view with materialized view
-- Save existing view definition
CREATE OR REPLACE VIEW pg_stat_monitor_old AS
SELECT * FROM pg_stat_monitor;
-- Drop existing view
DROP VIEW IF EXISTS pg_stat_monitor;
-- Create materialized view from table data
CREATE MATERIALIZED VIEW pg_stat_monitor AS
SELECT
bucket_id,
queryid,
dbid,
userid,
calls,
rows,
total_time,
mean_time,
min_time,
max_time,
shared_blks_hit,
shared_blks_read
FROM pg_stat_monitor_data
WHERE exported_at > now() - interval '24 hours';
-- Create unique index for CONCURRENT refresh
CREATE UNIQUE INDEX ON pg_stat_monitor (bucket_id, queryid, dbid, userid);
-- Initial population
REFRESH MATERIALIZED VIEW pg_stat_monitor;
```
## **Phase 2 Testing**
```sql
-- Query the materialized view
SELECT * FROM pg_stat_monitor LIMIT 10;
-- Verify refresh timing matches bucket rotation
-- With default pgsm_bucket_time=60, view should refresh every 60 seconds
-- Check PostgreSQL logs for: "pg_stat_monitor: refreshed materialized view"
-- Test with different bucket timing
ALTER SYSTEM SET pg_stat_monitor.pgsm_bucket_time = 30; -- 30-second buckets
SELECT pg_reload_conf();
-- Now view should refresh every 30 seconds
```
---
# **PHASE 3: Memory Reduction to 1-3MB (2 hours)**
*Git diff: ~100 lines, mostly in isolated functions*
## **Objective**
Clear buckets immediately after export to achieve 1-3MB memory usage.
## **Changes**
### **3.1: Immediate Clear After Export** (`pgsm_table_export.c`)
```c
/*
* Clear all entries from exported bucket
* This allows us to keep only current data in memory
*/
void
pgsm_clear_bucket_after_export(uint64 bucket_id)
{
HASH_SEQ_STATUS hash_seq;
pgsmEntry *entry;
int cleared = 0;
/* Iterate and remove entries from exported bucket */
hash_seq_init(&hash_seq, pgsm_hash);
while ((entry = hash_seq_search(&hash_seq)) != NULL)
{
if (entry->key.bucket_id == bucket_id)
{
/* Remove from hash table */
hash_search(pgsm_hash, &entry->key, HASH_REMOVE, NULL);
cleared++;
}
}
elog(DEBUG1, "pg_stat_monitor: cleared %d entries from bucket %lu",
cleared, bucket_id);
}
```
### **3.2: Modify Export Flow** (`pg_stat_monitor.c`)
```diff
static uint64
get_next_wbucket(pgsmSharedState *pgsm)
{
if (update_bucket)
{
new_bucket_id = (tv.tv_sec / pgsm_bucket_time) % pgsm_max_buckets;
prev_bucket_id = pg_atomic_exchange_u64(&pgsm->current_wbucket, new_bucket_id);
pgsm_lock_aquire(pgsm, LW_EXCLUSIVE);
/* Export bucket data before deallocation */
pgsm_export_bucket_to_table(new_bucket_id);
+ /* Clear exported bucket immediately to free memory */
+ extern void pgsm_clear_bucket_after_export(uint64);
+ pgsm_clear_bucket_after_export(new_bucket_id);
- hash_entry_dealloc(new_bucket_id, prev_bucket_id, NULL);
+ /* Skip normal dealloc since we already cleared */
pgsm_lock_release(pgsm);
}
}
```
### **3.3: Single Bucket Mode** (`guc.c`)
```diff
void
init_guc(void)
{
+ /* Override to single bucket for minimal memory */
+ if (pgsm_enable_table_export)
+ pgsm_max_buckets = 1; /* Only current bucket needed */
```
### **3.4: Further Memory Reduction**
```sql
-- Phase 3: Aggressive memory reduction
ALTER SYSTEM SET pg_stat_monitor.pgsm_max = '1MB'; -- Minimum possible
ALTER SYSTEM SET pg_stat_monitor.pgsm_max_buckets = 1; -- Single bucket
ALTER SYSTEM SET pg_stat_monitor.pgsm_query_shared_buffer = '100kB'; -- Tiny buffer
```
## **Phase 3 Testing**
```sql
-- Check memory usage
SELECT name, size FROM pg_shmem_allocations
WHERE name LIKE '%pg_stat_monitor%';
-- Should show ~1-3MB instead of 276MB
```
---
## **Summary of Changes**
| Phase | Files Changed | Lines Added | Memory Usage | Feature |
|-------|--------------|-------------|--------------|---------|
| **Phase 1** | 4 files | ~150 lines | 11MB | Table export |
| **Phase 2** | 2 files | ~30 lines | 11MB | Mat view + bucket-synced refresh |
| **Phase 3** | 3 files | ~100 lines | **1-3MB** | Clear after export |
**Total Git Diff: ~300 lines across 5 files**
## **Key Benefits**
1. **Phased approach** - Each phase can be reviewed/tested independently
2. **Minimal core changes** - Hooks into existing bucket rotation
3. **No cron needed** - Uses existing function calls for timing
4. **Easy rollback** - Can disable with single GUC
5. **Rebase friendly** - Changes isolated in new file + minimal hooks

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/* contrib/pg_stat_monitor/pg_stat_monitor--2.3--2.4.sql */
-- complain if script is sourced in psql, rather than via CREATE EXTENSION
\echo Use "ALTER EXTENSION pg_stat_monitor" to load this file. \quit
-- Create partitioned table with exact pg_stat_monitor API structure
-- Table columns match the expected API exactly - direct table access
DROP VIEW IF EXISTS pg_stat_monitor CASCADE;
CREATE TABLE pg_stat_monitor (
bucket bigint, -- renamed from bucket_id
bucket_start_time timestamptz,
userid oid,
username text,
dbid oid,
datname text,
client_ip inet,
pgsm_query_id bigint,
queryid bigint,
toplevel boolean,
top_queryid bigint,
-- Query texts limited to 1.5KB each
query text,
comments text,
planid bigint,
query_plan text,
top_query text,
application_name text,
relations text[], -- array instead of comma-separated string
cmd_type int,
cmd_type_text text, -- computed at write time
elevel int,
sqlcode text,
message text,
-- Execution stats
calls bigint,
total_exec_time double precision,
min_exec_time double precision,
max_exec_time double precision,
mean_exec_time double precision,
stddev_exec_time double precision,
rows bigint,
-- Planning stats
plans bigint,
total_plan_time double precision,
min_plan_time double precision,
max_plan_time double precision,
mean_plan_time double precision,
stddev_plan_time double precision,
-- Block stats
shared_blks_hit bigint,
shared_blks_read bigint,
shared_blks_dirtied bigint,
shared_blks_written bigint,
local_blks_hit bigint,
local_blks_read bigint,
local_blks_dirtied bigint,
local_blks_written bigint,
temp_blks_read bigint,
temp_blks_written bigint,
shared_blk_read_time double precision,
shared_blk_write_time double precision,
local_blk_read_time double precision,
local_blk_write_time double precision,
temp_blk_read_time double precision,
temp_blk_write_time double precision,
-- System stats
cpu_user_time double precision,
cpu_sys_time double precision,
-- WAL stats
wal_records bigint,
wal_fpi bigint,
wal_bytes numeric,
-- JIT stats
jit_functions bigint,
jit_generation_time double precision,
jit_inlining_count bigint,
jit_inlining_time double precision,
jit_optimization_count bigint,
jit_optimization_time double precision,
jit_emission_count bigint,
jit_emission_time double precision,
jit_deform_count bigint,
jit_deform_time double precision,
-- Response time histogram
resp_calls text[],
-- Metadata
stats_since timestamptz,
minmax_stats_since timestamptz,
bucket_done boolean DEFAULT false,
exported_at timestamptz DEFAULT now()
) PARTITION BY RANGE (exported_at);
-- Create initial partition for today
CREATE TABLE pg_stat_monitor_default
PARTITION OF pg_stat_monitor DEFAULT;
-- Create indexes for query performance
CREATE INDEX ON pg_stat_monitor (queryid);
CREATE INDEX ON pg_stat_monitor (exported_at);
CREATE INDEX ON pg_stat_monitor (bucket, queryid); -- Composite for time-series queries
-- Configure memory and query text limits (set these manually in postgresql.conf):
-- pg_stat_monitor.pgsm_max = '10MB'
-- pg_stat_monitor.pgsm_max_buckets = 2
-- pg_stat_monitor.pgsm_query_shared_buffer = '1MB'
-- pg_stat_monitor.pgsm_query_max_len = 1536
-- Create user-callable export function following PostgreSQL extension best practices
CREATE OR REPLACE FUNCTION pg_stat_monitor_export()
RETURNS int
AS 'MODULE_PATHNAME', 'pg_stat_monitor_export'
LANGUAGE C STRICT VOLATILE;
-- Grant execute permission to public
GRANT EXECUTE ON FUNCTION pg_stat_monitor_export() TO PUBLIC;
-- Table structure matches API exactly - implementation complete

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pg_stat_monitor.h
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@ -503,3 +503,6 @@ void pgsm_hash_seq_init(PGSM_HASH_SEQ_STATUS * hstat, PGSM_HASH_TABLE * shared_
void *pgsm_hash_seq_next(PGSM_HASH_SEQ_STATUS * hstat);
void pgsm_hash_seq_term(PGSM_HASH_SEQ_STATUS * hstat);
void pgsm_hash_delete_current(PGSM_HASH_SEQ_STATUS * hstat, PGSM_HASH_TABLE * shared_hash, void *key);
/* Table export functions */
bool pgsm_export_bucket_to_table(uint64 bucket_id);

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/*
* pgsm_table_export.c - Export pg_stat_monitor data to partitioned tables
* Low-memory implementation with query text limits and top queries filtering
*/
#include "postgres.h"
#include "pg_stat_monitor.h"
#include "executor/spi.h"
#include "utils/builtins.h"
#include "utils/timestamp.h"
#include "catalog/pg_authid.h"
#include "lib/dshash.h"
#include "utils/dsa.h"
/* Helper macro for repeated truncate and escape pattern */
#define APPEND_ESCAPED_STRING(sql, str, max_len) \
do { \
if ((str) && strlen(str) > 0) { \
char *escaped = truncate_and_escape_string((str), (max_len)); \
appendStringInfo(&(sql), "'%s', ", escaped); \
pfree(escaped); \
} else { \
appendStringInfo(&(sql), "NULL, "); \
} \
} while(0)
/* Function declarations */
bool pgsm_export_bucket_to_table(uint64 bucket_id);
/* Configuration */
#define MAX_QUERY_LENGTH 1536 /* 1.5KB limit for query text */
#define MAX_QUERIES_PER_BUCKET 300 /* Top 300 queries per bucket */
/* External references */
extern pgsmSharedState *pgsm_get_ss(void);
extern dsa_area *get_dsa_area_for_query_text(void);
/* Structure for sorting entries by total_time */
typedef struct
{
pgsmEntry *entry;
double total_time;
} EntryWithTime;
/*
* Helper function to truncate and escape strings for SQL
*/
static char *
truncate_and_escape_string(const char *str, int max_len)
{
int len;
bool truncated;
char *result;
int src_len;
int j = 0;
if (!str || *str == '\0')
return pstrdup("");
len = strlen(str);
truncated = (len > max_len);
/* Simple approach: allocate generous buffer */
src_len = truncated ? max_len : len;
result = palloc(src_len * 2 + 10);
/* Copy and escape quotes */
for (int i = 0; i < src_len; i++)
{
if (str[i] == '\'')
{
result[j++] = '\'';
result[j++] = '\'';
}
else
{
result[j++] = str[i];
}
}
/* Add truncation marker if needed */
if (truncated)
{
result[j++] = '.';
result[j++] = '.';
result[j++] = '.';
}
result[j] = '\0';
return result;
}
/*
* Helper to convert response calls array to PostgreSQL array format
*/
static char *
resp_calls_to_array(int *resp_calls, int count)
{
StringInfoData str;
char *result;
initStringInfo(&str);
appendStringInfo(&str, "ARRAY[");
for (int i = 0; i < count; i++)
{
if (i > 0)
appendStringInfoChar(&str, ',');
appendStringInfo(&str, "%d", resp_calls[i]);
}
appendStringInfo(&str, "]");
/* Create a copy in the calling context and free the StringInfo */
result = pstrdup(str.data);
pfree(str.data);
return result;
}
/*
* Comparison function for sorting entries by total_time (descending)
*/
static int
compare_entries_by_time(const void *a, const void *b)
{
EntryWithTime *ea = (EntryWithTime *)a;
EntryWithTime *eb = (EntryWithTime *)b;
if (ea->total_time > eb->total_time)
return -1;
else if (ea->total_time < eb->total_time)
return 1;
else
return 0;
}
/*
* Helper function to collect and sort entries from a bucket
*/
static EntryWithTime *
collect_and_sort_entries(uint64 bucket_id, int *entry_count)
{
PGSM_HASH_SEQ_STATUS hstat;
pgsmEntry *entry;
EntryWithTime *entries_array = NULL;
int array_size = 1000; /* Initial allocation */
*entry_count = 0;
/* Allocate array for sorting entries */
entries_array = palloc(array_size * sizeof(EntryWithTime));
/* First pass: collect all entries from this bucket */
pgsm_hash_seq_init(&hstat, get_pgsmHash(), false);
while ((entry = pgsm_hash_seq_next(&hstat)) != NULL)
{
if (entry->key.bucket_id != bucket_id)
continue;
/* Expand array if needed */
if (*entry_count >= array_size)
{
array_size *= 2;
entries_array = repalloc(entries_array, array_size * sizeof(EntryWithTime));
}
entries_array[*entry_count].entry = entry;
entries_array[*entry_count].total_time = entry->counters.time.total_time;
(*entry_count)++;
}
pgsm_hash_seq_term(&hstat);
elog(LOG, "pg_stat_monitor: Found %d entries for bucket %lu", *entry_count, (unsigned long)bucket_id);
/* Sort entries by total_time descending */
qsort(entries_array, *entry_count, sizeof(EntryWithTime), compare_entries_by_time);
return entries_array;
}
/*
* Helper function to build INSERT SQL statement
*/
/*
* Build the INSERT statement header with all column names
*/
static void
build_insert_header(StringInfo sql)
{
appendStringInfo(sql,
"INSERT INTO pg_stat_monitor "
"(bucket, bucket_start_time, userid, username, dbid, datname, "
"client_ip, pgsm_query_id, queryid, toplevel, top_queryid, "
"query, comments, planid, query_plan, top_query, application_name, relations, "
"cmd_type, cmd_type_text, elevel, sqlcode, message, "
"calls, total_exec_time, min_exec_time, max_exec_time, mean_exec_time, stddev_exec_time, rows, "
"plans, total_plan_time, min_plan_time, max_plan_time, mean_plan_time, stddev_plan_time, "
"shared_blks_hit, shared_blks_read, shared_blks_dirtied, shared_blks_written, "
"local_blks_hit, local_blks_read, local_blks_dirtied, local_blks_written, "
"temp_blks_read, temp_blks_written, "
"shared_blk_read_time, shared_blk_write_time, local_blk_read_time, local_blk_write_time, "
"temp_blk_read_time, temp_blk_write_time, "
"cpu_user_time, cpu_sys_time, "
"wal_records, wal_fpi, wal_bytes, "
"jit_functions, jit_generation_time, jit_inlining_count, jit_inlining_time, "
"jit_optimization_count, jit_optimization_time, jit_emission_count, jit_emission_time, "
"jit_deform_count, jit_deform_time, "
"resp_calls, stats_since, minmax_stats_since, bucket_done, exported_at"
") VALUES ");
}
static char *
build_insert_statement(EntryWithTime *entries_array, int queries_to_export,
uint64 bucket_id, pgsmSharedState *pgsm, dsa_area *query_dsa_area)
{
StringInfoData sql;
bool first = true;
/* Build batch INSERT for top queries */
initStringInfo(&sql);
build_insert_header(&sql);
/* Export top N entries using original incremental approach */
for (int i = 0; i < queries_to_export; i++)
{
char *query_txt = NULL;
char *parent_query_txt = NULL;
char *query_plan_txt = NULL;
char *relations_str = NULL;
double exec_stddev = 0.0;
double plan_stddev = 0.0;
double plan_mean __attribute__((unused)) = 0.0;
char *resp_calls_str;
pgsmEntry *entry;
entry = entries_array[i].entry;
if (!first)
appendStringInfoChar(&sql, ',');
first = false;
/* Get query text - truncated to MAX_QUERY_LENGTH */
if (DsaPointerIsValid(entry->query_text.query_pos))
{
char *query_ptr = dsa_get_address(query_dsa_area, entry->query_text.query_pos);
query_txt = truncate_and_escape_string(query_ptr, MAX_QUERY_LENGTH);
}
else
{
query_txt = pstrdup("Query string not available");
}
/* Get parent query text if exists - also truncated */
if (entry->key.parentid != UINT64CONST(0) &&
DsaPointerIsValid(entry->counters.info.parent_query))
{
char *query_ptr = dsa_get_address(query_dsa_area, entry->counters.info.parent_query);
parent_query_txt = truncate_and_escape_string(query_ptr, MAX_QUERY_LENGTH);
}
/* Get relations as comma-separated string */
if (entry->counters.info.num_relations > 0)
{
StringInfoData rel_str;
initStringInfo(&rel_str);
for (int j = 0; j < entry->counters.info.num_relations; j++)
{
if (j > 0)
appendStringInfoChar(&rel_str, ',');
appendStringInfo(&rel_str, "%s", entry->counters.info.relations[j]);
}
/* Create a copy in the calling context and free the StringInfo */
relations_str = pstrdup(rel_str.data);
pfree(rel_str.data);
}
/* Calculate stddev for exec and plan times */
if (entry->counters.calls.calls > 1)
exec_stddev = sqrt(entry->counters.time.sum_var_time / entry->counters.calls.calls);
if (entry->counters.plancalls.calls > 1)
{
plan_stddev = sqrt(entry->counters.plantime.sum_var_time / entry->counters.plancalls.calls);
plan_mean = entry->counters.plantime.mean_time;
}
/* Convert response calls array to PostgreSQL array */
resp_calls_str = resp_calls_to_array(entry->counters.resp_calls, MAX_RESPONSE_BUCKET);
/* Get query plan if exists - also truncated */
if (entry->key.planid && entry->counters.planinfo.plan_text[0])
{
query_plan_txt = truncate_and_escape_string(entry->counters.planinfo.plan_text, MAX_QUERY_LENGTH);
}
/* Build the VALUES clause for this entry */
appendStringInfo(&sql,
"("
"%ld, ", /* bucket_id */
(int64)bucket_id);
/* bucket_start_time */
if (pgsm->bucket_start_time[bucket_id] != 0)
appendStringInfo(&sql, "to_timestamp(%f)::timestamptz, ",
(double)(pgsm->bucket_start_time[bucket_id] / 1000000.0));
else
appendStringInfo(&sql, "NULL, ");
{
char *username_escaped = truncate_and_escape_string(entry->username, NAMEDATALEN);
char *datname_escaped = truncate_and_escape_string(entry->datname, NAMEDATALEN);
appendStringInfo(&sql, "%u, '%s', %u, '%s', ",
entry->key.userid, username_escaped, entry->key.dbid, datname_escaped);
pfree(username_escaped);
pfree(datname_escaped);
}
/* client_ip */
if (entry->key.ip != 0)
appendStringInfo(&sql, "'0.0.0.0'::inet + %ld, ", (int64)entry->key.ip);
else
appendStringInfo(&sql, "NULL, ");
/* pgsm_query_id, queryid */
appendStringInfo(&sql, "%ld, %ld, ",
(int64)entry->pgsm_query_id,
(int64)entry->key.queryid);
/* toplevel */
appendStringInfo(&sql, "%s, ", entry->key.toplevel ? "true" : "false");
/* top_queryid */
if (entry->key.parentid != UINT64CONST(0))
appendStringInfo(&sql, "%ld, ", (int64)entry->key.parentid);
else
appendStringInfo(&sql, "NULL, ");
/* query */
appendStringInfo(&sql, "'%s', ", query_txt);
/* comments */
APPEND_ESCAPED_STRING(sql, entry->counters.info.comments, 256);
/* planid */
if (entry->key.planid)
appendStringInfo(&sql, "%ld, ", (int64)entry->key.planid);
else
appendStringInfo(&sql, "NULL, ");
/* query_plan */
if (query_plan_txt)
appendStringInfo(&sql, "'%s', ", query_plan_txt);
else
appendStringInfo(&sql, "NULL, ");
/* top_query */
if (parent_query_txt)
appendStringInfo(&sql, "'%s', ", parent_query_txt);
else
appendStringInfo(&sql, "NULL, ");
/* application_name */
APPEND_ESCAPED_STRING(sql, entry->counters.info.application_name, NAMEDATALEN);
/* relations - convert to PostgreSQL array format */
if (relations_str && strlen(relations_str) > 0)
{
char *relations_copy;
char *token;
bool first_rel = true;
appendStringInfo(&sql, "ARRAY[");
relations_copy = pstrdup(relations_str);
token = strtok(relations_copy, ",");
while (token != NULL)
{
if (!first_rel)
appendStringInfoChar(&sql, ',');
appendStringInfo(&sql, "'%s'", token);
first_rel = false;
token = strtok(NULL, ",");
}
appendStringInfo(&sql, "], ");
pfree(relations_copy);
}
else
appendStringInfo(&sql, "NULL, ");
/* cmd_type */
if (entry->counters.info.cmd_type != CMD_NOTHING)
appendStringInfo(&sql, "%d, ", entry->counters.info.cmd_type);
else
appendStringInfo(&sql, "NULL, ");
/* cmd_type_text - convert to text */
switch (entry->counters.info.cmd_type)
{
case CMD_SELECT:
appendStringInfo(&sql, "'SELECT', ");
break;
case CMD_UPDATE:
appendStringInfo(&sql, "'UPDATE', ");
break;
case CMD_INSERT:
appendStringInfo(&sql, "'INSERT', ");
break;
case CMD_DELETE:
appendStringInfo(&sql, "'DELETE', ");
break;
case CMD_UTILITY:
appendStringInfo(&sql, "'UTILITY', ");
break;
case CMD_NOTHING:
default:
appendStringInfo(&sql, "NULL, ");
break;
}
/* elevel, sqlcode, message */
appendStringInfo(&sql, "%ld, ", (long)entry->counters.error.elevel);
APPEND_ESCAPED_STRING(sql, entry->counters.error.sqlcode, 5);
APPEND_ESCAPED_STRING(sql, entry->counters.error.message, 256);
/* Execution stats */
appendStringInfo(&sql,
"%ld, %.3f, %.3f, %.3f, %.3f, %.3f, %ld, ",
entry->counters.calls.calls,
entry->counters.time.total_time,
entry->counters.time.min_time,
entry->counters.time.max_time,
entry->counters.time.mean_time,
exec_stddev,
entry->counters.calls.rows);
/* Planning stats */
appendStringInfo(&sql,
"%ld, %.3f, %.3f, %.3f, %.3f, %.3f, ",
entry->counters.plancalls.calls,
entry->counters.plantime.total_time,
entry->counters.plantime.min_time,
entry->counters.plantime.max_time,
entry->counters.plantime.mean_time,
plan_stddev);
/* Block stats */
appendStringInfo(&sql,
"%ld, %ld, %ld, %ld, %ld, %ld, %ld, %ld, %ld, %ld, "
"%.3f, %.3f, %.3f, %.3f, %.3f, %.3f, ",
entry->counters.blocks.shared_blks_hit,
entry->counters.blocks.shared_blks_read,
entry->counters.blocks.shared_blks_dirtied,
entry->counters.blocks.shared_blks_written,
entry->counters.blocks.local_blks_hit,
entry->counters.blocks.local_blks_read,
entry->counters.blocks.local_blks_dirtied,
entry->counters.blocks.local_blks_written,
entry->counters.blocks.temp_blks_read,
entry->counters.blocks.temp_blks_written,
entry->counters.blocks.shared_blk_read_time,
entry->counters.blocks.shared_blk_write_time,
entry->counters.blocks.local_blk_read_time,
entry->counters.blocks.local_blk_write_time,
entry->counters.blocks.temp_blk_read_time,
entry->counters.blocks.temp_blk_write_time);
/* System stats */
appendStringInfo(&sql,
"%.3f, %.3f, ",
entry->counters.sysinfo.utime,
entry->counters.sysinfo.stime);
/* WAL stats */
appendStringInfo(&sql,
"%ld, %ld, %ld, ",
entry->counters.walusage.wal_records,
entry->counters.walusage.wal_fpi,
(int64)entry->counters.walusage.wal_bytes);
/* JIT stats */
appendStringInfo(&sql,
"%ld, %.3f, %ld, %.3f, %ld, %.3f, %ld, %.3f, %ld, %.3f, ",
entry->counters.jitinfo.jit_functions,
entry->counters.jitinfo.jit_generation_time,
entry->counters.jitinfo.jit_inlining_count,
entry->counters.jitinfo.jit_inlining_time,
entry->counters.jitinfo.jit_optimization_count,
entry->counters.jitinfo.jit_optimization_time,
entry->counters.jitinfo.jit_emission_count,
entry->counters.jitinfo.jit_emission_time,
entry->counters.jitinfo.jit_deform_count,
entry->counters.jitinfo.jit_deform_time);
/* resp_calls */
appendStringInfo(&sql, "%s, ", resp_calls_str);
/* stats_since, minmax_stats_since */
if (entry->stats_since != 0)
appendStringInfo(&sql, "to_timestamp(%f)::timestamptz, ",
(double)(entry->stats_since / 1000000.0));
else
appendStringInfo(&sql, "NULL, ");
if (entry->minmax_stats_since != 0)
appendStringInfo(&sql, "to_timestamp(%f)::timestamptz, ",
(double)(entry->minmax_stats_since / 1000000.0));
else
appendStringInfo(&sql, "NULL, ");
/* bucket_done - mark as false since bucket is still active */
appendStringInfo(&sql, "false, ");
/* exported_at - use current timestamp */
appendStringInfo(&sql, "now())");
/* Clean up */
if (query_txt)
pfree(query_txt);
if (parent_query_txt)
pfree(parent_query_txt);
if (query_plan_txt)
pfree(query_plan_txt);
if (relations_str)
pfree(relations_str);
if (resp_calls_str)
pfree(resp_calls_str);
}
{
char *result = pstrdup(sql.data);
/* StringInfo manages its own memory - don't call pfree on sql.data */
return result;
}
}
/*
* Helper function to execute SQL statement
*/
static bool
execute_export_sql(const char *sql, uint64 bucket_id, int exported)
{
int spi_result;
int ret;
bool export_successful = false;
bool spi_connected = false;
elog(LOG, "pg_stat_monitor: About to export %d queries for bucket %lu", exported, (unsigned long)bucket_id);
/* Attempt SPI execution with proper error handling */
PG_TRY();
{
/* Try to connect to SPI manager */
spi_result = SPI_connect();
if (spi_result != SPI_OK_CONNECT)
{
elog(DEBUG1, "pg_stat_monitor: Deferring export of bucket %lu (SPI connect failed: %d)",
(unsigned long)bucket_id, spi_result);
export_successful = false;
}
else
{
spi_connected = true;
/* Execute the INSERT statement */
elog(LOG, "pg_stat_monitor: Executing SQL for bucket %lu", (unsigned long)bucket_id);
elog(LOG, "pg_stat_monitor: FULL SQL: %s", sql);
/* Add pre-execution debugging */
elog(LOG, "pg_stat_monitor: About to call SPI_execute");
elog(LOG, "pg_stat_monitor: SPI connection status: %d", SPI_result);
ret = SPI_execute(sql, false, 0);
elog(LOG, "pg_stat_monitor: SPI_execute returned: %d", ret);
elog(LOG, "pg_stat_monitor: SPI_OK_INSERT value is: %d", SPI_OK_INSERT);
elog(LOG, "pg_stat_monitor: SPI_processed: %lu", (unsigned long)SPI_processed);
/* Check result */
if (ret == SPI_OK_INSERT)
{
elog(LOG, "pg_stat_monitor: Successfully exported %d queries for bucket %lu",
exported, (unsigned long)bucket_id);
export_successful = true;
}
else
{
elog(WARNING, "pg_stat_monitor: Failed to insert bucket %lu data, SPI result: %d",
(unsigned long)bucket_id, ret);
export_successful = false;
}
/* Always call SPI_finish() after successful SPI_connect() */
SPI_finish();
spi_connected = false;
}
}
PG_CATCH();
{
/* Handle SPI context errors gracefully */
ErrorData *errdata;
/* Clean up SPI connection if it was established */
if (spi_connected)
{
SPI_finish();
}
errdata = CopyErrorData();
elog(DEBUG1, "pg_stat_monitor: Export deferred for bucket %lu: %s",
(unsigned long)bucket_id, errdata->message);
FreeErrorData(errdata);
FlushErrorState();
export_successful = false;
}
PG_END_TRY();
return export_successful;
}
/*
* Export bucket data to partitioned table
* Called from ExecutorEnd when a bucket needs export
* Returns true if export succeeded or no data to export, false if deferred
*/
bool
pgsm_export_bucket_to_table(uint64 bucket_id)
{
EntryWithTime *entries_array = NULL;
char *sql = NULL;
pgsmSharedState *pgsm;
dsa_area *query_dsa_area;
int entry_count, queries_to_export;
bool export_successful = false;
/* Log when export function is called */
elog(DEBUG1, "pg_stat_monitor: Export function called for bucket %lu", (unsigned long)bucket_id);
/* Get shared memory areas */
pgsm = pgsm_get_ss();
query_dsa_area = get_dsa_area_for_query_text();
/* Step 1: Collect and sort entries from this bucket */
entries_array = collect_and_sort_entries(bucket_id, &entry_count);
/* Step 2: Limit to top N queries */
queries_to_export = (entry_count > MAX_QUERIES_PER_BUCKET) ?
MAX_QUERIES_PER_BUCKET : entry_count;
if (queries_to_export == 0)
{
elog(DEBUG1, "pg_stat_monitor: No data to export for bucket %lu (found %d entries)",
(unsigned long)bucket_id, entry_count);
export_successful = true; /* No data to export is success */
goto cleanup;
}
/* Step 3: Build INSERT SQL statement */
sql = build_insert_statement(entries_array, queries_to_export, bucket_id, pgsm, query_dsa_area);
/* Step 4: Execute SQL statement */
export_successful = execute_export_sql(sql, bucket_id, queries_to_export);
elog(LOG, "pg_stat_monitor: execute_export_sql returned %s for bucket %lu",
export_successful ? "true" : "false", (unsigned long)bucket_id);
cleanup:
/* Single cleanup point to avoid double-free errors */
if (sql)
pfree(sql);
if (entries_array)
pfree(entries_array);
elog(LOG, "pg_stat_monitor: pgsm_export_bucket_to_table returning %s for bucket %lu",
export_successful ? "true" : "false", (unsigned long)bucket_id);
return export_successful;
}
/*
* User-callable export function following PostgreSQL extension best practices
* This is the safe way to trigger exports - from a proper transaction context
* Similar to pg_stat_statements_reset() pattern
*/
PG_FUNCTION_INFO_V1(pg_stat_monitor_export);
Datum
pg_stat_monitor_export(PG_FUNCTION_ARGS)
{
pgsmSharedState *pgsm = pgsm_get_ss();
uint64 bucket_to_export;
uint64 current_bucket_id;
int exported_buckets = 0;
/* Check if user has appropriate permissions */
if (!superuser())
ereport(ERROR,
(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
errmsg("must be superuser to export pg_stat_monitor data")));
/* Get current bucket ID */
current_bucket_id = pg_atomic_read_u64(&pgsm->current_wbucket);
/* Check for pending exports */
bucket_to_export = pg_atomic_read_u64(&pgsm->bucket_to_export);
/* Determine which bucket to export */
{
uint64 target_bucket = (bucket_to_export == (uint64)-1) ? current_bucket_id : bucket_to_export;
/* Export the target bucket */
if (pgsm_export_bucket_to_table(target_bucket))
{
exported_buckets = 1;
/* Clear export flag if it was a pending export */
if (bucket_to_export != (uint64)-1)
pg_atomic_compare_exchange_u64(&pgsm->bucket_to_export, &bucket_to_export, (uint64)-1);
}
}
PG_RETURN_INT32(exported_buckets);
}