Hello,
I try change column encoding, but it doesn't work as expected.
My test:
I have table :
openx=> select export_objects('','test.test1');
export_objects
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
CREATE TABLE test.test1
(
language_id int
);
CREATE PROJECTION test.test1 /*+createtype(P)*/
(
language_id
)
AS
SELECT test1.language_id
FROM test.test1
ORDER BY test1.language_id
SEGMENTED BY hash(test1.language_id) ALL NODES KSAFE 1;
Check size
SELECT
projection_name,
column_name,
encodings,
compressions,
ROUND(SUM(used_bytes)/(1024^2),1)::FLOAT AS size_Mb
FROM
column_storage
WHERE
anchor_table_name = 'test1'
and projection_schema = 'test'
-- and projection_name = 'mnt_compiled_stats_full_new_b0'
GROUP BY
1,2,3,4
ORDER BY
5 DESC;
projection_name | column_name | encodings | compressions | size_Mb
-----------------+-------------+--------------+--------------+---------
test1_b0 | language_id | Uncompressed | int delta | 7005
test1_b1 | language_id | Uncompressed | int delta | 7005
test1_b0 | epoch | Int_Delta | none | 41
test1_b1 | epoch | Int_Delta | none | 41
Tnen, i change encoding and execute mergeout
openx=> alter table test.test1 alter column language_id encoding BLOCK_DICT projections (test.test1_b0,test.test1_b1);
WARNING 9385: New encoding will not be applied to existing projection data of this table; this change will be applied only on mergeout
ALTER TABLE
openx=> select do_tm_task('mergeout','test.test1');
do_tm_task
-----------------------------------------------------------------------------------------------------------------
Task: mergeout
(Table: test.test1) (Projection: test.test1_b0)
(Table: test.test1) (Projection: test.test1_b1)
(1 row)
Check size again - nothing changed.
projection_name column_name encodings compressions size_Mb --------------- ----------- ------------ ------------ ------- test1_b0 language_id Uncompressed int delta 7005.0 test1_b1 language_id Uncompressed int delta 7005.0 test1_b0 epoch Int_Delta none 41.0 test1_b1 epoch Int_Delta none 41.0
Vertica vertsion
openx=> SELECT version();
version
-------------------------------------
Vertica Analytic Database v10.0.0-3
