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ASF GitHub Bot commented on DRILL-6791: --------------------------------------- paul-rogers opened a new pull request #1501: DRILL-6791: Scan projection framework URL: https://github.com/apache/drill/pull/1501 The "schema projection" mechanism: * Handles none (SELECT COUNT\(*)), some (SELECT a, b, x) and all (SELECT *) projection. * Handles null columns (for projection a column "x" that does not exist in the base table.) * Handles constant columns as used for file metadata (AKA "implicit" columns). * Handle schema persistence: the need to reuse the same vectors across different scanners * Provides a framework for consuming externally-supplied metadata * Since we don't yet have a way to provide "real" metadata, obtains metadata hints from previous batches and from the projection list (a.b implies that "a" is a map, c[0] implies that "c" is an array, etc.) * Handles merging the set of data source columns and null columns to create the final output batch. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org > Merge scan projection framework into master > ------------------------------------------- > > Key: DRILL-6791 > URL: https://issues.apache.org/jira/browse/DRILL-6791 > Project: Apache Drill > Issue Type: Improvement > Affects Versions: 1.15.0 > Reporter: Paul Rogers > Assignee: Paul Rogers > Priority: Major > > Merge the next set of "result set loader" code into master via a PR. This one > covers the "schema projection" mechanism which: > * Handles none (SELECT COUNT\(*)), some (SELECT a, b, x) and all (SELECT *) > projection. > * Handles null columns (for projection a column "x" that does not exist in > the base table.) > * Handles constant columns as used for file metadata (AKA "implicit" columns). > * Handle schema persistence: the need to reuse the same vectors across > different scanners > * Provides a framework for consuming externally-supplied metadata > * Since we don't yet have a way to provide "real" metadata, obtains metadata > hints from previous batches and from the projection list (a.b implies that > "a" is a map, c[0] implies that "c" is an array, etc.) > * Handles merging the set of data source columns and null columns to create > the final output batch. -- This message was sent by Atlassian JIRA (v7.6.3#76005)