Details
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Task
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Status: Closed (View Workflow)
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Minor
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Resolution: Duplicate
Description
Assume strict mode is enabled and I have to update 10000 rows in a table with 100000 rows. The updates are independent of each other (so update xbt_files set leechers = 1 where fid in (1,2) doesn't work).
Executing 10000 queries isn't efficient. There's a nice trick via insert ... on duplicate key update, but it breaks in strict mode (and strict mode is good, so I don't want to disable it).
Another way is to execute the updates via update ... case ... when ... then ... else ... end. However, this way can be 20x slower (for 10000 updates) and the syntax is worse.
So I'd like to request support for bulk updates. I think batch/bulk updates are a common operation and deserve proper and efficient support.
Possible syntax:
update2 xbt_files (fid, leechers, seeders, completed) values (3,1,2,3),(2,4,5,6) set |
leechers = values(leechers), seeders = values(seeders), completed = values(completed); |
The syntax is just a possibility, the semantics are the most important part.
How to repeat:
set sql_mode = ''; |
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drop table if exists xbt_files; |
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create table xbt_files |
(
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fid int not null auto_increment, |
info_hash blob not null, |
leechers int not null default 0, |
seeders int not null default 0, |
completed int not null default 0, |
flags int not null default 0, |
mtime int not null, |
ctime int not null, |
primary key (fid), |
unique key (info_hash(20)) |
);
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insert into xbt_files (info_hash, mtime, ctime) values ('oRUImUWFyXvKItw3tVfB', |
unix_timestamp(), unix_timestamp()), ('7XnB2eksvUgHvavG3YPJ', unix_timestamp(), |
unix_timestamp()), ('9EsYv9y72FuHsL5yQYf8', unix_timestamp(), unix_timestamp()); |
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insert into xbt_files (fid, leechers, seeders, completed) values (2,6268,4510,38453) on |
duplicate key update leechers = values(leechers), seeders = values(seeders), completed = |
values(completed); |
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update xbt_files set leechers = case fid when 2 then 4 else leechers end, seeders = case |
fid when 2 then 5 else seeders end, completed = case fid when 2 then 6 else completed end |
where fid in (2); |
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set sql_mode = 'strict_all_tables'; |
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insert into xbt_files (fid, leechers, seeders, completed) values (3,6268,4510,38453) on |
duplicate key update leechers = values(leechers), seeders = values(seeders), completed = |
values(completed); |
# ERROR 1364 (HY000): Field 'info_hash' doesn't have a default value |
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update xbt_files set leechers = case fid when 3 then 7 else leechers end, seeders = case |
fid when 3 then 8 else seeders end, completed = case fid when 3 then 9 else completed end |
where fid in (3); |
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select * from xbt_files; |
Attachments
Issue Links
- duplicates
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MDEV-38885 Bulk Update statement
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- Open
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- links to