Use ColumnarIndexScan for ORDER BY LIMIT 1 queries - #10476
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@natalya-aksman, @dbeck: please review this pull request.
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Create ColumnarIndexScan paths for eligible queries when all required columns can be reconstructed from segment-by columns and sparse order-by metadata. This allows boundary rows to be returned without decompressing batches. Extend the plan and executor output mapping to support projected scan paths as well as aggregate rewrites. Only select the optimization when all qualifications are pushed down and no decompression recheck is required.
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akuzm
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Aug 31, 2026
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| static bool | ||
| columnar_index_scan_query_supported(PlannerInfo *root) |
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Why is columnar index scan planning is now in columnar scan planning? Shouldn't we keep them separate?
akuzm
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Aug 31, 2026
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| static CustomPathMethods columnar_index_scan_path_methods = { | ||
| .CustomName = COLUMNAR_INDEX_SCAN_NAME, | ||
| .PlanCustomPath = columnar_index_scan_plan_path, |
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Why did you decide to switch to cost-based planning for columnar index scan? Isn't it still absolutely better when applicable? I liked that we could skip the cost-based planning for it, because this requires less code and makes planning faster.
akuzm
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Aug 31, 2026
| List *targetlist, List *custom_scan_tlist, | ||
| List *exec_output_map, int flags); | ||
| extern Node *columnar_index_scan_state_create(CustomScan *cscan); | ||
| extern Plan *try_insert_columnar_index_scan_node(Plan *plan, List *rtable); |
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Are you also keeping the old planning metod in addition to the new planning method?
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Create ColumnarIndexScan paths for eligible queries when all required
columns can be reconstructed from segment-by columns and sparse
order-by metadata. This allows boundary rows to be returned without
decompressing batches.
Extend the plan and executor output mapping to support projected scan
paths as well as aggregate rewrites. Only select the optimization when
all qualifications are pushed down and no decompression recheck is
required.