This document shows you how to tune your indexes to achieve faster query performance and better recall.
Analyze your queries
Use the EXPLAIN ANALYZE command to analyze your query insights as shown in the following example SQL query.
EXPLAINANALYZESELECTresult-columnFROMmy-tableORDERBYEMBEDDING_COLUMN<->embedding('text-embedding-005','What is a database?')::vectorLIMIT1;
The example response QUERY PLAN includes information such as the time taken, the number of rows scanned or returned, and the resources used.
Limit (cost=0.42..15.27 rows=1 width=32) (actual time=0.106..0.132 rows=1 loops=1)
-> Index Scan using my-scann-index on my-table (cost=0.42..858027.93 rows=100000 width=32) (actual time=0.105..0.129 rows=1 loops=1)
Order By: (embedding_column <-> embedding('text-embedding-005', 'What is a database?')::vector(768))
Limit value: 1
Planning Time: 0.354 ms
Execution Time: 0.141 ms
View vector index metrics
You can use the vector index metrics to review performance of your vector index,
identify areas for improvement, and tune your index based on the metrics, if
needed.
To view all vector index metrics, run the following SQL query, which uses the
pg_stat_ann_indexes view:
SELECT*FROMpg_stat_ann_indexes;
For more information about the complete list of metrics, see Vector index
metrics.
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Hard to understand","hardToUnderstand","thumb-down"],["Incorrect information or sample code","incorrectInformationOrSampleCode","thumb-down"],["Missing the information/samples I need","missingTheInformationSamplesINeed","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-25 UTC."],[[["\u003cp\u003eThis document guides users on tuning indexes for enhanced query speed and improved recall.\u003c/p\u003e\n"],["\u003cp\u003eUtilize the \u003ccode\u003eEXPLAIN ANALYZE\u003c/code\u003e command to gain insights into query performance, including time taken, rows scanned, and resource consumption.\u003c/p\u003e\n"],["\u003cp\u003eVector index metrics, accessible via the \u003ccode\u003epg_stat_ann_indexes\u003c/code\u003e view, allow for performance assessment and index tuning.\u003c/p\u003e\n"],["\u003cp\u003eThe provided content contains examples for both query plan analysis, and SQL commands for performance assessment of vector indexes.\u003c/p\u003e\n"]]],[],null,["# Tune vector query performance\n\nSelect a documentation version: 15.7.0keyboard_arrow_down\n\n- [Current (16.8.0)](/alloydb/omni/current/docs/ai/tune-indexes)\n- [16.8.0](/alloydb/omni/16.8.0/docs/ai/tune-indexes)\n- [16.3.0](/alloydb/omni/16.3.0/docs/ai/tune-indexes)\n- [15.12.0](/alloydb/omni/15.12.0/docs/ai/tune-indexes)\n- [15.7.1](/alloydb/omni/15.7.1/docs/ai/tune-indexes)\n- [15.7.0](/alloydb/omni/15.7.0/docs/ai/tune-indexes)\n\n\u003cbr /\u003e\n\nThis document shows you how to tune your indexes to achieve faster query performance and better recall. \nScaNN IVF IVFFlat HNSW\n\nAnalyze your queries\n--------------------\n\nUse the `EXPLAIN ANALYZE` command to analyze your query insights as shown in the following example SQL query. \n\n EXPLAIN ANALYZE SELECT result-column\n FROM my-table\n ORDER BY EMBEDDING_COLUMN \u003c-\u003e embedding('text-embedding-005', 'What is a database?')::vector\n LIMIT 1;\n\nThe example response `QUERY PLAN` includes information such as the time taken, the number of rows scanned or returned, and the resources used. \n\n Limit (cost=0.42..15.27 rows=1 width=32) (actual time=0.106..0.132 rows=1 loops=1)\n -\u003e Index Scan using my-scann-index on my-table (cost=0.42..858027.93 rows=100000 width=32) (actual time=0.105..0.129 rows=1 loops=1)\n Order By: (embedding_column \u003c-\u003e embedding('text-embedding-005', 'What is a database?')::vector(768))\n Limit value: 1\n Planning Time: 0.354 ms\n Execution Time: 0.141 ms\n\nView vector index metrics\n-------------------------\n\nYou can use the vector index metrics to review performance of your vector index,\nidentify areas for improvement, and tune your index based on the metrics, if\nneeded.\n\nTo view all vector index metrics, run the following SQL query, which uses the\n`pg_stat_ann_indexes` view: \n\n SELECT * FROM pg_stat_ann_indexes;\n\nFor more information about the complete list of metrics, see [Vector index\nmetrics](/alloydb/docs/reference/vector-index-metrics).\n\nWhat's next\n-----------\n\n- [An example embedding workflow](/alloydb/omni/15.7.0/docs/ai/example-embeddings)"]]