Details
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Type:
Task
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Status: Closed
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Priority:
Major
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Resolution: Fixed
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Fix Version/s: 5.3.5
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Component/s: None
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Labels:None
Description
We need statistics counters for MRR. In particular, we need
- How many MRR scans were performed
- How many key/rowid re-sort operations were made (Need separate counters for key and rowid ops).
The first attempt at counters was:
- Handler_mrr_init,
- Handler_mrr_extra_rowid_sorts,
- Handler_mrr_extra_key_sorts
(see http://kb.askmonty.org/en/multi-range-read-optimization#counters for docs)
However, the names/semantics were deemed too complicated. Now, we need to come up with simpler definitions.
== Proposal#1 ==
- Handler_mrr_init - stays the same, counts rowid-ordered scans, key-ordered scans, and key-ordered rowid-ordered scans
- Handler_mrr_rowid_ordered_passes - counts number of
{ sort rowids; do a rowid-ordered read sweep; }
passes
- Handler_mrr_key_ordered_passes - counts number of
{ sort keys; do a key-ordered read sweep; }
passes
== Proposal#2 ==
Same as above but break Handler_mrr_init into three:
- Handler_mrr_key_ordered
- Handler_mrr_rowid_ordered
- Handler_mrr_key_rowid_ordered
== Decision ==
On the last optimizer call, we've decided to go with these counters:
Handler_mrr_init
Handler_mrr_key_refills
Handler_mrr_rowid_refills
and the first fill is not counted as a "refill".
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Counters, as they are added, are inappropriate (Igor's feedback). We'll need to fix them.
current counters:
- Handler_mrr_init - counts how many MRR scans were performed
- Handler_mrr_extra_rowid_sorts - counts rowid sort operations done in MRR scans, except the first scan in each operation
- Handler_mrr_extra_key_sorts - counts key sort operations done in MRR scans, except the first scan in each operation
Push the patch with the new names.
New counters were pushed.
This is now coded, pushed, and documented.