From 7d4afec31e8498a660b61944557e8623e565746c Mon Sep 17 00:00:00 2001 From: happenlee Date: Tue, 22 Sep 2026 15:28:06 +0800 Subject: [PATCH] [improvement](fe) Set minimum scanner concurrency to 4 ### What problem does this PR solve? Issue Number: None Related PR: #63389 Problem Summary: New sessions currently use `min_scanners_concurrency = 1`. Raise this default to `4` and update its description so regular scans use a higher concurrency floor under the existing scanner-count, concurrency, and memory limits. Serial scans continue to use one scanner. Expression ZoneMap filtering is already enabled by default on master (`enable_expr_zonemap_filter = true`). ### Release note Increase the default `min_scanners_concurrency` from `1` to `4` for new sessions. ### Check List (For Author) - Test: FE unit tests and Checkstyle passed. - `MAVEN_ARGS='-T 48' bash run-fe-ut.sh --run org.apache.doris.qe.SessionVariablesTest,org.apache.doris.qe.VariableMgrTest`: 31 tests, 0 failures/errors/skips. - `mvn -T 48 checkstyle:check -pl fe-core` (from `fe/`): 0 violations. - `git diff --check`: passed. - Behavior changed: Yes. New sessions default to a minimum scanner concurrency of 4. - Does this need documentation: No. The session-variable description is updated with the new default. --- .../src/main/java/org/apache/doris/qe/SessionVariable.java | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/fe/fe-core/src/main/java/org/apache/doris/qe/SessionVariable.java b/fe/fe-core/src/main/java/org/apache/doris/qe/SessionVariable.java index 9e40aa4869c539..0387a26e007a58 100644 --- a/fe/fe-core/src/main/java/org/apache/doris/qe/SessionVariable.java +++ b/fe/fe-core/src/main/java/org/apache/doris/qe/SessionVariable.java @@ -1171,8 +1171,8 @@ public static double getHotValueThreshold() { public int localExchangeFreeBlocksLimit = 4; @VarAttrDef.VarAttr(name = MIN_SCANNERS_CONCURRENCY, needForward = true, description = "The min concurrency of " - + "Scanner, default 1") - public int minScannersConcurrency = 1; + + "Scanner, default 4") + public int minScannersConcurrency = 4; @VarAttrDef.VarAttr(name = MIN_FILE_SCANNERS_CONCURRENCY, needForward = true, description = "The min concurrency " + "of Remote Scanner, default 1")