*: replace cost model factor constants with system variable #12367
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eurekaka
added
type/enhancement
Codecov Report
@@ Coverage Diff @@
## master #12367 +/- ##
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Coverage ? 80.7625%
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Files ? 454
Lines ? 99431
Branches ? 0
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Hits ? 80303
Misses ? 13336
Partials ? 5792 |
eurekaka
requested review from
winoros,
zz-jason,
alivxxx,
lzmhhh123 and
francis0407
zz-jason
reviewed
Sep 25, 2019
| // tidb_opt_memory_factor is the memory cost of storing one tuple. | ||
| TiDBOptMemoryFactor = "tidb_opt_memory_factor" | ||
| // tidb_opt_concurrency_factor is the CPU cost of additional one goroutine. | ||
| TiDBOptConcurrencyFactor = "tidb_opt_concurrency_factor" |
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How about renaming them in the format of tidb_opt_factor_xxx? So that we can search all the factors with a simple sql like show variables like "tidb_opt_factor%.
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It would look strange for variables like tidb_opt_factor_cpu, we can use show variables like "tidb_opt_%_factor" to query all the values instead?
| } | ||
| if v < 0 { | ||
| return value, ErrWrongValueForVar.GenWithStackByArgs(name, value) | ||
| } |
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should we validate the upper limit for each variable?
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How should we set the upper limit for the variables?
lzmhhh123
reviewed
Sep 25, 2019
lzmhhh123
added
status/can-merge
|
/run-all-tests |
lzmhhh123
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Jan 19, 2020
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What problem does this PR solve?
As the title said, replace hard-coded cost model factor constants with system variables, to make it more flexible for re-configuration to fit into customized environments.
What is changed and how it works?
Add 7 system variables corresponding to the constant factors, and use them in cost computing.
Check List
Tests
Code changes
Side effects
N/A
Related changes
Release note
N/A