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Removing the cap on the # of iterations of SplitQuery. #2651

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Merged
erzel merged 1 commit into from
Mar 22, 2017
+4 −7
Merged

Removing the cap on the # of iterations of SplitQuery. #2651

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11 changes: 4 additions & 7 deletions go/vt/vttablet/tabletserver/splitquery/full_scan_algorithm.go
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Original file line number Diff line number Diff line change
Expand Up @@ -77,14 +77,11 @@ func (a *FullScanAlgorithm) generateBoundaries() ([]tuple, error) {
}
result := make([]tuple, 0, a.splitParams.splitCount)
var iteration int64
// We have to allow for more than splitCount query-parts since we use an estimated
// tableSize in the equation 'numRowsPerQueryPart * splitCount = tableSize'.
maxIterations := 10 * a.splitParams.splitCount
// We used to have a safety check that makes sure the number of iterations does not
// exceed 10*a.splitParams.splitCount. The splitCount parameter was calculated from
// the estimated number of rows in the information schema, which could have been grossly
// inaccurate (more than 10 times too low).
for iteration = 0; prevTuple != nil; iteration++ {
if iteration > maxIterations {
panic(fmt.Sprintf("splitquery.FullScanAlgorithm.generateBoundaries(): didn't terminate"+
" after %v iterations (=10*splitCount). FullScanAlgorithm: %v", maxIterations, a))
}
result = append(result, prevTuple)
a.populatePrevTupleInBindVariables(prevTuple, a.noninitialQuery.BindVariables)
prevTuple, err = a.executeQuery(a.noninitialQuery)
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