external
/
citus
mirror of https://github.com/citusdata/citus.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

Merge pull request #5189 from citusdata/col/readme-updates 

Update columnar readme for temporary table & index support
pull/5168/head^2
Onur Tirtir 2021-08-23 10:38:52 +03:00 committed by GitHub
parent 262f89359e 7dcd9380e7
commit 2b93f8af56
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 9 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

15
src/backend/columnar/README.md
View File

@ -41,7 +41,7 @@ Benefits of Citus Columnar over cstore_fdw:
* Append-only (no ``UPDATE``/``DELETE`` support) * Append-only (no ``UPDATE``/``DELETE`` support)
* No space reclamation (e.g. rolled-back transactions may still * No space reclamation (e.g. rolled-back transactions may still
consume disk space) consume disk space)
* No index support, index scans, or bitmap index scans * No bitmap index scans
* No tidscans * No tidscans
* No sample scans * No sample scans
* No TOAST support (large values supported inline) * No TOAST support (large values supported inline)
@ -58,7 +58,6 @@ Benefits of Citus Columnar over cstore_fdw:
* No support for intra-node parallel scans * No support for intra-node parallel scans
* No support for ``AFTER ... FOR EACH ROW`` triggers * No support for ``AFTER ... FOR EACH ROW`` triggers
* No `UNLOGGED` columnar tables * No `UNLOGGED` columnar tables
* No `TEMPORARY` columnar tables
Future iterations will incrementally lift the limitations listed above. Future iterations will incrementally lift the limitations listed above.
@ -188,10 +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 data to be updated only affects row tables (e.g. ``UPDATE parent SET
i = i + 1 WHERE n = 300``). i = i + 1 WHERE n = 300``).
Because columnar tables do not support indexes, it's impossible to Note that Citus Columnar supports `btree` and `hash `indexes (and
create indexes on the partitioned table if some partitions are the constraints requiring them) but does not support `gist`, `gin`,
columnar. Instead, you must create indexes on the individual row `spgist` and `brin` indexes.
partitions. Similarly for constraints that require indexes, e.g.: 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 ```sql
CREATE INDEX p2_ts_idx ON p2 (ts); CREATE INDEX p2_ts_idx ON p2 (ts);