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Improved examples [skip ci]

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This commit is contained in:
Andrew Kane
2021-10-13 14:06:55 -07:00
parent b125b2debb
commit d52426b3fa
1 changed files with 8 additions and 8 deletions
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README.md
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@@ -4,7 +4,7 @@ Open-source vector similarity search for Postgres
```sql
CREATE TABLE table (column vector(3));
CREATE INDEX ON table USING ivfflat (column);
CREATE INDEX ON table USING ivfflat (column vector_l2_ops);
SELECT * FROM table ORDER BY column <-> '[1,2,3]' LIMIT 5;
```
@@ -62,7 +62,7 @@ Speed up queries with an approximate index. Add an index for each distance funct
L2 distance
```sql
CREATE INDEX ON table USING ivfflat (column vector_l2_ops); -- default if no opclass specified
CREATE INDEX ON table USING ivfflat (column vector_l2_ops);
```
Inner product
@@ -83,8 +83,8 @@ Indexes should be created after the table has data for optimal clustering. If th
-- Postgres 12+
REINDEX INDEX CONCURRENTLY index_name;
-- Postgres < 12 (change opclass as needed)
CREATE INDEX CONCURRENTLY temp_name ON table USING ivfflat (column vector_l2_ops);
-- Postgres < 12
CREATE INDEX CONCURRENTLY temp_name ON table USING ivfflat (column opclass);
DROP INDEX CONCURRENTLY index_name;
ALTER INDEX temp_name RENAME TO index_name;
```
@@ -96,7 +96,7 @@ Also, unlike typical indexes which only affect performance, you may see differen
Specify the number of inverted lists (100 by default)
```sql
CREATE INDEX ON table USING ivfflat (column) WITH (lists = 100);
CREATE INDEX ON table USING ivfflat (column opclass) WITH (lists = 100);
```
### Query Options
@@ -123,7 +123,7 @@ COMMIT;
Consider [partial indexes](https://www.postgresql.org/docs/current/indexes-partial.html) for queries with a `WHERE` clause
```sql
CREATE INDEX ON table USING ivfflat (column) WHERE (other_column = 123);
CREATE INDEX ON table USING ivfflat (column opclass) WHERE (other_column = 123);
```
To index many different values of `other_column`, consider [partitioning](https://www.postgresql.org/docs/current/ddl-partitioning.html) on `other_column`.
@@ -136,10 +136,10 @@ To speed up queries without an index, increase `max_parallel_workers_per_gather`
SET max_parallel_workers_per_gather = 4;
```
To speed up queries with an index, increase the number of inverted lists.
To speed up queries with an index, increase the number of inverted lists (at the expense of recall).
```sql
CREATE INDEX ON table USING ivfflat (column) WITH (lists = 1000);
CREATE INDEX ON table USING ivfflat (column opclass) WITH (lists = 1000);
```
## Reference