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feat(database_observability.postgres): Add configurable limit to pg_stat_statements query #5639

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Merged
cristiangreco merged 1 commit into from
Mar 13, 2026
Merged

feat(database_observability.postgres): Add configurable limit to pg_stat_statements query #5639

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1 change: 1 addition & 0 deletions .../reference/components/database_observability/database_observability.postgres.md
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Original file line number Diff line number Diff line change
Expand Up @@ -117,6 +117,7 @@ The `azure` block supplies the identifying information for the database being mo
| Name | Type | Description | Default | Required |
|--------------------|------------|------------------------------------------------------|---------|----------|
| `collect_interval` | `duration` | How frequently to collect information from database. | `"1m"` | no |
| `statements_limit` | `integer` | Max number of recent queries to collect details for. | `100` | no |
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@cristiangreco cristiangreco Feb 24, 2026

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100 matches the default value of postgres_exporter (and our previously hardcoded value)


### `query_samples`

Expand Down
7 changes: 5 additions & 2 deletions internal/component/database_observability/postgres/collector/query_details.go
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Expand Up @@ -41,12 +41,13 @@ var selectQueriesFromActivity = `
AND pg_database.datname NOT IN %s
%s
ORDER BY total_exec_time DESC
LIMIT 100
LIMIT %d
`

type QueryDetailsArguments struct {
DB *sql.DB
CollectInterval time.Duration
StatementsLimit int
ExcludeDatabases []string
ExcludeUsers []string
EntryHandler loki.EntryHandler
Expand All @@ -58,6 +59,7 @@ type QueryDetailsArguments struct {
type QueryDetails struct {
dbConnection *sql.DB
collectInterval time.Duration
statementsLimit int
excludeDatabases []string
excludeUsers []string
entryHandler loki.EntryHandler
Expand All @@ -74,6 +76,7 @@ func NewQueryDetails(args QueryDetailsArguments) (*QueryDetails, error) {
return &QueryDetails{
dbConnection: args.DB,
collectInterval: args.CollectInterval,
statementsLimit: args.StatementsLimit,
excludeDatabases: args.ExcludeDatabases,
excludeUsers: args.ExcludeUsers,
entryHandler: args.EntryHandler,
Expand Down Expand Up @@ -133,7 +136,7 @@ func (c *QueryDetails) Stop() {
func (c QueryDetails) fetchAndAssociate(ctx context.Context) error {
excludedDatabasesClause := buildExcludedDatabasesClause(c.excludeDatabases)
excludedUsersClause := buildExcludedUsersClause(c.excludeUsers, "pg_get_userbyid(pg_stat_statements.userid)")
query := fmt.Sprintf(selectQueriesFromActivity, excludedDatabasesClause, excludedUsersClause)
query := fmt.Sprintf(selectQueriesFromActivity, excludedDatabasesClause, excludedUsersClause, c.statementsLimit)
rs, err := c.dbConnection.QueryContext(ctx, query)
if err != nil {
return fmt.Errorf("failed to fetch statements from pg_stat_statements view: %w", err)
Expand Down
22 changes: 14 additions & 8 deletions internal/component/database_observability/postgres/collector/query_details_test.go
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Expand Up @@ -500,14 +500,15 @@ func TestQueryDetails(t *testing.T) {
collector, err := NewQueryDetails(QueryDetailsArguments{
DB: db,
CollectInterval: time.Second,
StatementsLimit: 100,
EntryHandler: lokiClient,
TableRegistry: tc.tableRegistry,
Logger: log.NewLogfmtLogger(os.Stderr),
})
require.NoError(t, err)
require.NotNil(t, collector)

mock.ExpectQuery(fmt.Sprintf(selectQueriesFromActivity, exclusionClause, "")).WithoutArgs().RowsWillBeClosed().
mock.ExpectQuery(fmt.Sprintf(selectQueriesFromActivity, exclusionClause, "", 100)).WithoutArgs().RowsWillBeClosed().
WillReturnRows(
sqlmock.NewRows([]string{
"queryid",
Expand Down Expand Up @@ -562,21 +563,22 @@ func TestQueryDetails_SQLDriverErrors(t *testing.T) {
collector, err := NewQueryDetails(QueryDetailsArguments{
DB: db,
CollectInterval: time.Second,
StatementsLimit: 100,
EntryHandler: lokiClient,
Logger: log.NewLogfmtLogger(os.Stderr),
})
require.NoError(t, err)
require.NotNil(t, collector)

mock.ExpectQuery(fmt.Sprintf(selectQueriesFromActivity, exclusionClause, "")).WithoutArgs().RowsWillBeClosed().
mock.ExpectQuery(fmt.Sprintf(selectQueriesFromActivity, exclusionClause, "", 100)).WithoutArgs().RowsWillBeClosed().
WillReturnRows(
sqlmock.NewRows([]string{
"queryid", // not enough columns
}).AddRow(
"abc123",
))

mock.ExpectQuery(fmt.Sprintf(selectQueriesFromActivity, exclusionClause, "")).WithoutArgs().RowsWillBeClosed().
mock.ExpectQuery(fmt.Sprintf(selectQueriesFromActivity, exclusionClause, "", 100)).WithoutArgs().RowsWillBeClosed().
WillReturnRows(
sqlmock.NewRows([]string{
"queryid",
Expand Down Expand Up @@ -625,13 +627,14 @@ func TestQueryDetails_SQLDriverErrors(t *testing.T) {
collector, err := NewQueryDetails(QueryDetailsArguments{
DB: db,
CollectInterval: time.Second,
StatementsLimit: 100,
EntryHandler: lokiClient,
Logger: log.NewLogfmtLogger(os.Stderr),
})
require.NoError(t, err)
require.NotNil(t, collector)

mock.ExpectQuery(fmt.Sprintf(selectQueriesFromActivity, exclusionClause, "")).WithoutArgs().RowsWillBeClosed().
mock.ExpectQuery(fmt.Sprintf(selectQueriesFromActivity, exclusionClause, "", 100)).WithoutArgs().RowsWillBeClosed().
WillReturnRows(
sqlmock.NewRows([]string{
"queryid",
Expand Down Expand Up @@ -684,15 +687,16 @@ func TestQueryDetails_SQLDriverErrors(t *testing.T) {
collector, err := NewQueryDetails(QueryDetailsArguments{
DB: db,
CollectInterval: time.Second,
StatementsLimit: 100,
EntryHandler: lokiClient,
Logger: log.NewLogfmtLogger(os.Stderr),
})
require.NoError(t, err)
require.NotNil(t, collector)

mock.ExpectQuery(fmt.Sprintf(selectQueriesFromActivity, exclusionClause, "")).WithoutArgs().WillReturnError(fmt.Errorf("connection error"))
mock.ExpectQuery(fmt.Sprintf(selectQueriesFromActivity, exclusionClause, "", 100)).WithoutArgs().WillReturnError(fmt.Errorf("connection error"))

mock.ExpectQuery(fmt.Sprintf(selectQueriesFromActivity, exclusionClause, "")).WithoutArgs().RowsWillBeClosed().
mock.ExpectQuery(fmt.Sprintf(selectQueriesFromActivity, exclusionClause, "", 100)).WithoutArgs().RowsWillBeClosed().
WillReturnRows(
sqlmock.NewRows([]string{
"queryid",
Expand Down Expand Up @@ -904,14 +908,15 @@ func TestQueryDetails_ExcludeDatabases(t *testing.T) {
collector, err := NewQueryDetails(QueryDetailsArguments{
DB: db,
CollectInterval: time.Second,
StatementsLimit: 100,
ExcludeDatabases: []string{"excluded_database"},
EntryHandler: lokiClient,
Logger: log.NewLogfmtLogger(os.Stderr),
})
require.NoError(t, err)
require.NotNil(t, collector)

mock.ExpectQuery(fmt.Sprintf(selectQueriesFromActivity, buildExcludedDatabasesClause([]string{"excluded_database"}), "")).WithoutArgs().RowsWillBeClosed().
mock.ExpectQuery(fmt.Sprintf(selectQueriesFromActivity, buildExcludedDatabasesClause([]string{"excluded_database"}), "", 100)).WithoutArgs().RowsWillBeClosed().
WillReturnRows(
sqlmock.NewRows([]string{
"queryid",
Expand Down Expand Up @@ -959,6 +964,7 @@ func TestQueryDetails_ExcludeUsers(t *testing.T) {
collector, err := NewQueryDetails(QueryDetailsArguments{
DB: db,
CollectInterval: time.Second,
StatementsLimit: 100,
ExcludeUsers: []string{"excluded_user"},
EntryHandler: lokiClient,
Logger: log.NewLogfmtLogger(os.Stderr),
Expand All @@ -967,7 +973,7 @@ func TestQueryDetails_ExcludeUsers(t *testing.T) {
require.NotNil(t, collector)

expectedExcludedUsersClause := buildExcludedUsersClause([]string{"excluded_user"}, "pg_get_userbyid(pg_stat_statements.userid)")
mock.ExpectQuery(fmt.Sprintf(selectQueriesFromActivity, exclusionClause, expectedExcludedUsersClause)).WithoutArgs().RowsWillBeClosed().
mock.ExpectQuery(fmt.Sprintf(selectQueriesFromActivity, exclusionClause, expectedExcludedUsersClause, 100)).WithoutArgs().RowsWillBeClosed().
WillReturnRows(
sqlmock.NewRows([]string{
"queryid",
Expand Down
11 changes: 7 additions & 4 deletions internal/component/database_observability/postgres/component.go
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Expand Up @@ -70,7 +70,7 @@ type Arguments struct {

CloudProvider *CloudProvider `alloy:"cloud_provider,block,optional"`
QuerySampleArguments QuerySampleArguments `alloy:"query_samples,block,optional"`
QueryTablesArguments QueryTablesArguments `alloy:"query_details,block,optional"`
QueryDetailsArguments QueryDetailsArguments `alloy:"query_details,block,optional"`
SchemaDetailsArguments SchemaDetailsArguments `alloy:"schema_details,block,optional"`
ExplainPlansArguments ExplainPlansArguments `alloy:"explain_plans,block,optional"`
HealthCheckArguments HealthCheckArguments `alloy:"health_check,block,optional"`
Expand All @@ -97,8 +97,9 @@ type QuerySampleArguments struct {
ExcludeCurrentUser bool `alloy:"exclude_current_user,attr,optional"`
}

type QueryTablesArguments struct {
type QueryDetailsArguments struct {
CollectInterval time.Duration `alloy:"collect_interval,attr,optional"`
StatementsLimit int `alloy:"statements_limit,attr,optional"`
}

type SchemaDetailsArguments struct {
Expand All @@ -116,8 +117,9 @@ var DefaultArguments = Arguments{
DisableQueryRedaction: false,
ExcludeCurrentUser: true,
},
QueryTablesArguments: QueryTablesArguments{
QueryDetailsArguments: QueryDetailsArguments{
CollectInterval: 1 * time.Minute,
StatementsLimit: 100,
},
SchemaDetailsArguments: SchemaDetailsArguments{
CollectInterval: 1 * time.Minute,
Expand Down Expand Up @@ -470,7 +472,8 @@ func (c *Component) startCollectors(systemID string, engineVersion string, cloud
if collectors[collector.QueryDetailsCollector] {
qCollector, err := collector.NewQueryDetails(collector.QueryDetailsArguments{
DB: c.dbConnection,
CollectInterval: c.args.QueryTablesArguments.CollectInterval,
CollectInterval: c.args.QueryDetailsArguments.CollectInterval,
StatementsLimit: c.args.QueryDetailsArguments.StatementsLimit,
ExcludeDatabases: c.args.ExcludeDatabases,
ExcludeUsers: c.args.ExcludeUsers,
EntryHandler: entryHandler,
Expand Down
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