online_advisor

Overview

Requires shared_preload_libraries=online_advisor on PostgreSQL 14-16; PGSTY backports upstream PG18 hook compatibility.

Version

Build

You can build the RPM / DEB packages for online_advisor using pig build:

pig build pkg online_advisor         # build RPM / DEB packages

Install

You can install online_advisor directly. First, make sure the PGDG and PIGSTY repositories are added and enabled:

pig repo add pgsql -u          # Add repo and update cache

Install the extension using pig or apt/yum/dnf:

pig install online_advisor;          # Install for current active PG version

pig ext install -y online_advisor -v 18  # PG 18
pig ext install -y online_advisor -v 17  # PG 17
pig ext install -y online_advisor -v 16  # PG 16
pig ext install -y online_advisor -v 15  # PG 15
pig ext install -y online_advisor -v 14  # PG 14

dnf install -y online_advisor_18       # PG 18
dnf install -y online_advisor_17       # PG 17
dnf install -y online_advisor_16       # PG 16
dnf install -y online_advisor_15       # PG 15
dnf install -y online_advisor_14       # PG 14

apt install -y postgresql-18-online-advisor   # PG 18
apt install -y postgresql-17-online-advisor   # PG 17
apt install -y postgresql-16-online-advisor   # PG 16
apt install -y postgresql-15-online-advisor   # PG 15
apt install -y postgresql-14-online-advisor   # PG 14

Preload:

shared_preload_libraries = 'online_advisor';

Create Extension:

CREATE EXTENSION online_advisor;

Usage

Sources:

• Official README for version 1.0
• Extension control file
• Version 1.0 SQL objects
• Sample preload configuration

online_advisor observes PostgreSQL execution plans and workload timing, then recommends indexes, extended statistics, or prepared statements. It reports candidates only; it never creates an index or statistics object automatically.

Core Workflow

Preload the library and restart PostgreSQL:

shared_preload_libraries = 'online_advisor'

Create and activate the extension in each database whose workload should be observed:

CREATE EXTENSION online_advisor;

-- Calling an extension function activates collection in this database.
SELECT get_executor_stats();

After representative workload has run, inspect the recommendations:

SELECT * FROM proposed_indexes;
SELECT * FROM proposed_statistics;
SELECT * FROM get_executor_stats();

-- Keep separate index candidates instead of combining compatible clauses.
SELECT * FROM propose_indexes(combine => false);

Review each generated create_index or create_statistics statement before applying it. Run ANALYZE after creating an index or statistics object so the planner can use current statistics.

Objects and Settings

• proposed_indexes: view over propose_indexes(combine, reset) with filtering volume, call count, elapsed time, and a candidate CREATE INDEX statement.
• proposed_statistics: view over propose_statistics(combine, reset) with misestimation, call count, elapsed time, and a candidate CREATE STATISTICS statement.
• get_executor_stats(reset): returns aggregate planning and execution time, query count, and planning-overhead ratios.
• online_advisor.filtered_threshold: minimum filtered-row count considered for an index proposal; default 1000.
• online_advisor.misestimation_threshold: actual-to-estimated row ratio considered for statistics; default 10.
• online_advisor.min_rows: minimum returned rows for misestimation analysis; default 1000.
• online_advisor.max_index_proposals and online_advisor.max_stat_proposals: proposal capacities; set them before the extension is activated.
• online_advisor.do_instrumentation, online_advisor.log_duration, and online_advisor.prepare_threshold: control collection and prepared-statement advice.

Caveats

• Instrumentation adds workload overhead; measure it on the target system and disable collection when it is not needed.
• The index heuristic does not reason about operator ordering in compound indexes, join indexes, or indexes used only to avoid sorting.
• The extension does not estimate the benefit of a proposed index. Use plan review or a hypothetical-index tool before building expensive indexes.
• Advice is database-local and depends on the workload observed since activation or reset.