chibenwa commented on code in PR #2514:
URL: https://github.com/apache/james-project/pull/2514#discussion_r1858151717
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mailbox/postgres/src/main/java/org/apache/james/mailbox/postgres/mail/dao/PostgresMailboxMessageDAO.java:
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@@ -273,31 +270,55 @@ public Mono<Pair<Integer, Integer>>
countTotalAndUnseenMessagesByMailboxId(Postg
}
public Flux<Pair<SimpleMailboxMessage.Builder, Record>>
findMessagesByMailboxId(PostgresMailboxId mailboxId, Limit limit,
MessageMapper.FetchType fetchType) {
- PostgresMailboxMessageFetchStrategy fetchStrategy =
FETCH_TYPE_TO_FETCH_STRATEGY.apply(fetchType);
- Function<DSLContext, SelectSeekStep1<Record, Long>> queryWithoutLimit
= dslContext -> dslContext.select(fetchStrategy.fetchFields())
- .from(MESSAGES_JOIN_MAILBOX_MESSAGES_CONDITION_STEP)
- .where(MAILBOX_ID.eq(mailboxId.asUuid()))
- .orderBy(DEFAULT_SORT_ORDER_BY);
+ if (limit.isUnlimited()) {
+ return Flux.range(0, OFFSET_UNLIMITED)
+ .concatMap(offsetIndex ->
findMessagesByMailboxIdBatch(mailboxId, fetchType, offsetIndex *
queryBatchSize, queryBatchSize))
+ .takeUntil(List::isEmpty)
+ .flatMapIterable(Function.identity());
+ } else {
+ return findMessagesByMailboxIdBatch(mailboxId, fetchType, 0,
limit.getLimit().get())
+ .flatMapIterable(Function.identity());
+ }
+ }
- return postgresExecutor.executeRows(dslContext -> limit.getLimit()
- .map(limitValue -> Flux.from(queryWithoutLimit.andThen(step ->
step.limit(limitValue)).apply(dslContext)))
- .orElse(Flux.from(queryWithoutLimit.apply(dslContext))))
- .map(record ->
Pair.of(fetchStrategy.toMessageBuilder().apply(record), record));
+ private Mono<List<Pair<SimpleMailboxMessage.Builder, Record>>>
findMessagesByMailboxIdBatch(PostgresMailboxId mailboxId,
MessageMapper.FetchType fetchType, int offset, int batchSize) {
+ PostgresMailboxMessageFetchStrategy fetchStrategy =
FETCH_TYPE_TO_FETCH_STRATEGY.apply(fetchType);
+ return postgresExecutor.executeRows(dslContext ->
Flux.from(dslContext.select(fetchStrategy.fetchFields())
+ .from(MESSAGES_JOIN_MAILBOX_MESSAGES_CONDITION_STEP)
+ .where(MAILBOX_ID.eq(mailboxId.asUuid()))
+ .orderBy(DEFAULT_SORT_ORDER_BY)
+ .limit(batchSize)
+ .offset(offset)))
Review Comment:
Actually we would be WAY more resilient not using an offset. We SHALL reuse
the highest UID from the previous batch and resume from it. This would make us
reslient to deletion in already paged items.
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