Support and Constraints

A hybrid data warehouse is compatible with all column-store syntax.

**Table 1** Supported syntax
Syntax	Supported
CREATE TABLE	Yes
CREATE TABLE LIKE	Yes
DROP TABLE	Yes
INSERT	Yes
COPY	Yes
SELECT	Yes
TRUNCATE	Yes
EXPLAIN	Yes
ANALYZE	Yes
VACUUM	Yes
ALTER TABLE DROP PARTITION	Yes
ALTER TABLE ADD PARTITION	Yes
ALTER TABLE SET WITH OPTION	Yes
ALTER TABLE DROP COLUMN	Yes
ALTER TABLE ADD COLUMN	Yes
ALTER TABLE ADD NODELIST	Yes
ALTER TABLE CHANGE OWNER	Yes
ALTER TABLE RENAME COLUMN	Yes
ALTER TABLE TRUNCATE PARTITION	Yes
CREATE INDEX	Yes
DROP INDEX	Yes
DELETE	Yes
Other ALTER TABLE syntax	Yes
ALTER INDEX	Yes
MERGE	Yes
SELECT INTO	Yes
UPDATE	Yes
CREATE TABLE AS	Yes

To use HStore tables, use the following parameter settings, or the performance of HStore tables will deteriorate significantly:
autovacuum_max_workers_hstore=3, autovacuum_max_workers=6, and autovacuum=true
Currently, HStore and column storage do not support the use of VACUUM to clear dirty index data, and frequent updates may cause index bloat. This function will be supported in later versions.
When using HStore asynchronous sorting, pay attention to the following:
- DML operations on certain data may be blocked during asynchronous sorting. The maximum blocking granularity is the row threshold for asynchronous sorting. This function is not recommended for frequent DML operations.
- Automatic asynchronous sorting and column-store VACUUM cannot be used together. If the autovacuum process meets the conditions for column-store VACUUM, asynchronous sorting is skipped and will wait for the next trigger. In some cases, column-store VACUUM may be continuously triggered due to a high volume of DML operations, which means asynchronous sorting will never be triggered.