Hi,
On 07.02.20 09:25, Clemens Ladisch wrote:
Jürgen Baier wrote:
CREATE TABLE main ( ATT1 INT, ATT2 INT, PRIMARY KEY (ATT1,ATT2) );
CREATE TABLE staging ( ATT1 INT, ATT2 INT );
Then I execute
DELETE FROM main WHERE EXISTS (SELECT 1 FROM staging WHERE main.att1 =
staging.att1 AND main.att2 = staging.att2)
which takes a very long time.
DELETE FROM main WHERE (att1, att2) IN (SELECT att1, att2 FROM staging);
Thank you very much.
I can confirm that this solves my problem and indeed scans the staging
table and looks up the main table:
sqlite> EXPLAIN QUERY PLAN DELETE FROM main WHERE (att1, att2) IN
(SELECT att1, att2 FROM staging);
QUERY PLAN
|--SEARCH TABLE main USING INDEX sqlite_autoindex_main_1 (ATT1=? AND ATT2=?)
`--LIST SUBQUERY
`--SCAN TABLE staging
For reference: This syntax is not supported by Microsoft SQL Server
(2017). But Microsoft SQL Server is relatively fast when using the
original DELETE FROM query.
Thanks,
Jürgen
Regards,
Clemens
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