diff options
Diffstat (limited to 'src/backend')
| -rw-r--r-- | src/backend/utils/adt/orderedsetaggs.c | 34 |
1 files changed, 21 insertions, 13 deletions
diff --git a/src/backend/utils/adt/orderedsetaggs.c b/src/backend/utils/adt/orderedsetaggs.c index 135a14b0228..a290140e9c2 100644 --- a/src/backend/utils/adt/orderedsetaggs.c +++ b/src/backend/utils/adt/orderedsetaggs.c @@ -904,42 +904,50 @@ percentile_cont_multi_final_common(FunctionCallInfo fcinfo, for (; i < num_percentiles; i++) { - int64 target_row = pct_info[i].first_row; - bool need_lerp = (pct_info[i].second_row > target_row); + int64 first_row = pct_info[i].first_row; + int64 second_row = pct_info[i].second_row; int idx = pct_info[i].idx; - /* Advance to first_row, if not already there */ - if (target_row > rownum) + /* + * Advance to first_row, if not already there. Note that we might + * already have rownum beyond first_row, in which case first_val + * is already correct. (This occurs when interpolating between + * the same two input rows as for the previous percentile.) + */ + if (first_row > rownum) { - if (!tuplesort_skiptuples(osastate->sortstate, target_row - rownum - 1, true)) + if (!tuplesort_skiptuples(osastate->sortstate, first_row - rownum - 1, true)) elog(ERROR, "missing row in percentile_cont"); if (!tuplesort_getdatum(osastate->sortstate, true, &first_val, &isnull) || isnull) elog(ERROR, "missing row in percentile_cont"); - rownum = target_row; + rownum = first_row; + /* Always advance second_val to be latest input value */ + second_val = first_val; } - else + else if (first_row == rownum) { /* - * We are already at the target row, so we must previously - * have read its value into second_val. + * We are already at the desired row, so we must previously + * have read its value into second_val (and perhaps first_val + * as well, but this assignment is harmless in that case). */ first_val = second_val; } /* Fetch second_row if needed */ - if (need_lerp) + if (second_row > rownum) { if (!tuplesort_getdatum(osastate->sortstate, true, &second_val, &isnull) || isnull) elog(ERROR, "missing row in percentile_cont"); rownum++; } - else - second_val = first_val; + /* We should now certainly be on second_row exactly */ + Assert(second_row == rownum); /* Compute appropriate result */ - if (need_lerp) + if (second_row > first_row) result_datum[idx] = lerpfunc(first_val, second_val, pct_info[i].proportion); else |