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https://issues.apache.org/jira/browse/PHOENIX-4974?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16652612#comment-16652612
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Lars Hofhansl commented on PHOENIX-4974:
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Could also use {{connection.getRegionLocator(...).getAllRegionLocations()}}
I do wonder why it was done this way, though. Perhaps this makes sure we
absolutely have all key ranges covered, even as regions split or merge - ranges
might not perfectly match regions as they change, but we'd have no gaps for
sure.
> Gets all regions uses get requests is extremely slows for big table
> --------------------------------------------------------------------
>
> Key: PHOENIX-4974
> URL: https://issues.apache.org/jira/browse/PHOENIX-4974
> Project: Phoenix
> Issue Type: Improvement
> Affects Versions: 4.14.0, 5.0.0
> Reporter: Jaanai
> Assignee: Jaanai
> Priority: Blocker
> Attachments: PHOENIX-4974-master.patch, performance.png
>
>
> When executes the first query after started the client(SQLline or
> initializing JDBC client ), needs to load region locations to the client
> cache. Now the following is key implement :
> {code:java}
> List<HRegionLocation> locations = Lists.newArrayList();
> byte[] currentKey = HConstants.EMPTY_START_ROW;
> do {
> HRegionLocation regionLocation =
> connection.getRegionLocation(
> TableName.valueOf(tableName), currentKey, reload);
> locations.add(regionLocation);
> currentKey = regionLocation.getRegionInfo().getEndKey();
> } while (!Bytes.equals(currentKey, HConstants.EMPTY_END_ROW));
> {code}
> For some big tables which have more than ten thousand regions, this
> procedure is extremely slow.
> Runs a look points query on the table that has 10000 regions after starting
> the client, it needs 25+ seconds.
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