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https://issues.apache.org/jira/browse/DRILL-6099?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16379390#comment-16379390
]
ASF GitHub Bot commented on DRILL-6099:
---------------------------------------
Github user gparai commented on a diff in the pull request:
https://github.com/apache/drill/pull/1096#discussion_r171085780
--- Diff:
exec/java-exec/src/main/java/org/apache/drill/exec/planner/logical/DrillPushLimitToScanRule.java
---
@@ -55,18 +62,21 @@ public void onMatch(RelOptRuleCall call) {
}
};
- public static DrillPushLimitToScanRule LIMIT_ON_PROJECT =
- new DrillPushLimitToScanRule(
- RelOptHelper.some(DrillLimitRel.class, RelOptHelper.some(
- DrillProjectRel.class,
RelOptHelper.any(DrillScanRel.class))),
- "DrillPushLimitToScanRule_LimitOnProject") {
+ public static DrillPushLimitToScanRule LIMIT_ON_PROJECT = new
DrillPushLimitToScanRule(
+ RelOptHelper.some(DrillLimitRel.class,
RelOptHelper.any(DrillProjectRel.class)),
"DrillPushLimitToScanRule_LimitOnProject") {
@Override
public boolean matches(RelOptRuleCall call) {
DrillLimitRel limitRel = call.rel(0);
- DrillScanRel scanRel = call.rel(2);
- // For now only applies to Parquet. And pushdown only apply limit
but not offset,
+ DrillProjectRel projectRel = call.rel(1);
+ // pushdown only apply limit but not offset,
// so if getFetch() return null no need to run this rule.
- if (scanRel.getGroupScan().supportsLimitPushdown() &&
(limitRel.getFetch() != null)) {
--- End diff --
We still have the LIMIT_ON_SCAN rule which does that check. This rule is
changed from LIMIT_PROJECT_SCAN to LIMIT_PROJECT. The LIMIT_SCAN along with the
LIMIT_PROJECT would work as the LIMIT_PROJECT_SCAN.
> Drill does not push limit past project (flatten) if it cannot be pushed into
> scan
> ---------------------------------------------------------------------------------
>
> Key: DRILL-6099
> URL: https://issues.apache.org/jira/browse/DRILL-6099
> Project: Apache Drill
> Issue Type: Bug
> Affects Versions: 1.12.0
> Reporter: Gautam Kumar Parai
> Assignee: Gautam Kumar Parai
> Priority: Major
> Fix For: 1.13.0
>
>
> It would be useful to have pushdown occur past flatten(project). Here is an
> example to illustrate the issue:
> {{explain plan without implementation for }}{{select name,
> flatten(categories) as category from dfs.`/tmp/t_json_20` LIMIT 1;}}
> {{DrillScreenRel}}{{ }}
> {{ DrillLimitRel(fetch=[1])}}{{ }}
> {{ DrillProjectRel(name=[$0], category=[FLATTEN($1)])}}
> {{ DrillScanRel(table=[[dfs, /tmp/t_json_20]], groupscan=[EasyGroupScan
> [selectionRoot=maprfs:/tmp/t_json_20, numFiles=1, columns=[`name`,
> `categories`], files=[maprfs:///tmp/t_json_20/0_0_0.json]]])}}
> =================================================================
> Content of 0_0_0.json
> =================================================================
> {
> "name" : "Eric Goldberg, MD",
> "categories" : [ "Doctors", "Health & Medical" ]
> } {
> "name" : "Pine Cone Restaurant",
> "categories" : [ "Restaurants" ]
> } {
> "name" : "Deforest Family Restaurant",
> "categories" : [ "American (Traditional)", "Restaurants" ]
> } {
> "name" : "Culver's",
> "categories" : [ "Food", "Ice Cream & Frozen Yogurt", "Fast Food",
> "Restaurants" ]
> } {
> "name" : "Chang Jiang Chinese Kitchen",
> "categories" : [ "Chinese", "Restaurants" ]
> }
>
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