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Update index support section of columnar README

pull/5189/head
Onur Tirtir 2021-05-04 12:14:17 +03:00
parent 3acd3ebae2
commit 7dcd9380e7
1 changed files with 9 additions and 5 deletions
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14
src/backend/columnar/README.md
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@ -41,7 +41,7 @@ Benefits of Citus Columnar over cstore_fdw:
* Append-only (no ``UPDATE``/``DELETE`` support)
* No space reclamation (e.g. rolled-back transactions may still
consume disk space)
* No index support, index scans, or bitmap index scans
* No bitmap index scans
* No tidscans
* No sample scans
* No TOAST support (large values supported inline)
@ -187,10 +187,14 @@ operations that are supported on row tables but not columnar
data to be updated only affects row tables (e.g. ``UPDATE parent SET
i = i + 1 WHERE n = 300``).
Because columnar tables do not support indexes, it's impossible to
create indexes on the partitioned table if some partitions are
columnar. Instead, you must create indexes on the individual row
partitions. Similarly for constraints that require indexes, e.g.:
Note that Citus Columnar supports `btree` and `hash `indexes (and
the constraints requiring them) but does not support `gist`, `gin`,
`spgist` and `brin` indexes.
For this reason, if some partitions are columnar and if the index is
not supported by Citus Columnar, then it's impossible to create indexes
on the partitioned (parent) table directly. In that case, you need to
create the index on the individual row partitions. Similarly for the
constraints that require indexes, e.g.:
```sql
CREATE INDEX p2_ts_idx ON p2 (ts);