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Re: MDEV-21580: Allow packed sort keys in sort buffer
More input on the latest branch
* main/mdev21580.test is still there and the .result file is still too large.
* mysql-test/main/order_by_pack_big.result has got this:
+SELECT id, names, address INTO OUTFILE '/Users/varun/MariaDB/maria-dev2/mysql-test/var/mysqld.1/data/t1.txt' FROM t3 ORDER BY names, address;
please use 'evalp' to avoid this.
* The constant ORDER_BY_ORIGINAL_TRUNCATION is defined but not used anywhere?
On Wed, Feb 19, 2020 at 06:08:12PM +0300, Sergey Petrunia wrote:
> Hi Varun,
> Please find some input below.
> > commit f75829eebe96db55508cbc03c967e1c340da0cfc
> > Author: Varun Gupta <varun.gupta@xxxxxxxxxxx>
> > Date: Fri Feb 7 02:30:06 2020 +0530
> > MDEV-21580: Allow packed sort keys in sort buffer
> > This task deals with packing the sort key inside the sort buffer, which would
> > lead to efficient usage of the memory allocated for the sort buffer.
> > The changes brought by this feature are
> > 1) Sort buffers would have sort keys of variable length
> > 2) The format for sort keys inside the sort buffer would look like
> > |<sort_length><null_byte><key_part1><null_byte><key_part2>.......|
> > sort_length is the extra bytes that are required to store the variable
> > length of a sort key.
> > 3) When packing of sort key is done we store the ORIGINAL VALUES inside
> > the sort buffer and not the STRXFRM form (mem-comparable sort keys).
> > 4) Special comparison function packed_keys_comparison() is introduced
> > to compare 2 sort keys.
Sergei Petrunia, Software Developer
MariaDB Corporation | Skype: sergefp | Blog: http://s.petrunia.net/blog