diff options
| -rw-r--r-- | src/backend/optimizer/path/costsize.c | 35 |
1 files changed, 22 insertions, 13 deletions
diff --git a/src/backend/optimizer/path/costsize.c b/src/backend/optimizer/path/costsize.c index cd3716d494f..733f7ea5432 100644 --- a/src/backend/optimizer/path/costsize.c +++ b/src/backend/optimizer/path/costsize.c @@ -107,6 +107,13 @@ */ #define APPEND_CPU_COST_MULTIPLIER 0.5 +/* + * Maximum value for row estimates. We cap row estimates to this to help + * ensure that costs based on these estimates remain within the range of what + * double can represent. add_path() wouldn't act sanely given infinite or NaN + * cost values. + */ +#define MAXIMUM_ROWCOUNT 1e100 double seq_page_cost = DEFAULT_SEQ_PAGE_COST; double random_page_cost = DEFAULT_RANDOM_PAGE_COST; @@ -189,11 +196,14 @@ double clamp_row_est(double nrows) { /* - * Force estimate to be at least one row, to make explain output look - * better and to avoid possible divide-by-zero when interpolating costs. - * Make it an integer, too. + * Avoid infinite and NaN row estimates. Costs derived from such values + * are going to be useless. Also force the estimate to be at least one + * row, to make explain output look better and to avoid possible + * divide-by-zero when interpolating costs. Make it an integer, too. */ - if (nrows <= 1.0) + if (nrows > MAXIMUM_ROWCOUNT || isnan(nrows)) + nrows = MAXIMUM_ROWCOUNT; + else if (nrows <= 1.0) nrows = 1.0; else nrows = rint(nrows); @@ -2737,12 +2747,11 @@ final_cost_nestloop(PlannerInfo *root, NestPath *path, QualCost restrict_qual_cost; double ntuples; - /* Protect some assumptions below that rowcounts aren't zero or NaN */ - if (outer_path_rows <= 0 || isnan(outer_path_rows)) + /* Protect some assumptions below that rowcounts aren't zero */ + if (outer_path_rows <= 0) outer_path_rows = 1; - if (inner_path_rows <= 0 || isnan(inner_path_rows)) + if (inner_path_rows <= 0) inner_path_rows = 1; - /* Mark the path with the correct row estimate */ if (path->path.param_info) path->path.rows = path->path.param_info->ppi_rows; @@ -2952,10 +2961,10 @@ initial_cost_mergejoin(PlannerInfo *root, JoinCostWorkspace *workspace, innerendsel; Path sort_path; /* dummy for result of cost_sort */ - /* Protect some assumptions below that rowcounts aren't zero or NaN */ - if (outer_path_rows <= 0 || isnan(outer_path_rows)) + /* Protect some assumptions below that rowcounts aren't zero */ + if (outer_path_rows <= 0) outer_path_rows = 1; - if (inner_path_rows <= 0 || isnan(inner_path_rows)) + if (inner_path_rows <= 0) inner_path_rows = 1; /* @@ -3185,8 +3194,8 @@ final_cost_mergejoin(PlannerInfo *root, MergePath *path, rescannedtuples; double rescanratio; - /* Protect some assumptions below that rowcounts aren't zero or NaN */ - if (inner_path_rows <= 0 || isnan(inner_path_rows)) + /* Protect some assumptions below that rowcounts aren't zero */ + if (inner_path_rows <= 0) inner_path_rows = 1; /* Mark the path with the correct row estimate */ |