changliiu commented on code in PR #35042:
URL: https://github.com/apache/beam/pull/35042#discussion_r2114869392
##########
sdks/java/io/google-cloud-platform/src/main/java/org/apache/beam/sdk/io/gcp/spanner/changestreams/dao/PartitionMetadataDao.java:
##########
@@ -178,47 +179,57 @@ public List<String> findAllTableIndexes() {
*
* @return the earliest partition watermark which is not in a {@link
State#FINISHED} state.
*/
- public @Nullable Timestamp getUnfinishedMinWatermark() {
+ public @Nullable Timestamp getUnfinishedMinWatermark(Optional<Timestamp>
since) {
+ Timestamp sinceTimestamp = since.orElse(Timestamp.MIN_VALUE);
Statement statement;
+ final String minWatermark = "min_watermark";
if (this.isPostgres()) {
statement =
Statement.newBuilder(
- "SELECT \""
+ "SELECT min(\""
+ COLUMN_WATERMARK
- + "\" FROM \""
+ + "\") as "
+ + minWatermark
+ + " FROM \""
+ metadataTableName
+ "\" WHERE \""
+ COLUMN_STATE
+ "\" != $1"
- + " ORDER BY \""
+ + " AND \""
+ COLUMN_WATERMARK
- + "\" ASC LIMIT 1")
+ + "\" >= $2")
.bind("p1")
.to(State.FINISHED.name())
+ .bind("p2")
+ .to(sinceTimestamp)
.build();
} else {
statement =
Statement.newBuilder(
- "SELECT "
+ "SELECT min("
Review Comment:
There is a discussion to replace "limit 1" using "min()" in order to better
use the index. I agree that two queries can have the same result. Please
re-open if you have strong opinion on this. Thank you!
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