WL#13600: Deprecate system variable max_length_for_sort_data
Affects: Server-8.0 — Status: Complete
After fixing BUG#97154 (SORT SHORT BLOBS AS ADDON FIELDS), nothing will be using max_length_for_sort_data anymore, so we need to deprecate it. Currently, max_length_for_sort_data (default 4096) governs one and only one thing: If the maximum size of addon fields exceeds 4 kB, we will fall back to sorting row IDs (which is expensive, as we need to make a lot of random accesses to the table after the sort to actually get the data). However, the typical case for this is a JSON blob or geometry column; while they can theoretically be very large, yielding a huge maximum length, in practice they will be fairly small, and we get poor performance as a result. This is not to be confused with max_sort_length, which governs at which point we will start truncating sort _keys_ for blobs and strings with PAD SPACE collations.
F1. When trying to set the variable max_length_for_sort_data, one should get a deprecation warning.
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