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https://issues.apache.org/jira/browse/HBASE-5664?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13566279#comment-13566279
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Anoop Sam John commented on HBASE-5664:
---------------------------------------
[~lhofhansl]
The new CP call is in nextRow(byte [] currentRow, int offset, short length)
This method is called only when a row is filtered out.
{code}
if (filterRowKey(currentRow, offset, length)) {
- nextRow(currentRow, offset, length);
+ boolean moreRows = nextRow(currentRow, offset, length);
if (isEmptyRow || filterRow()) {
- nextRow(currentRow, offset, length);
+ boolean moreRows = nextRow(currentRow, offset, length);
if (results.isEmpty()) {
- nextRow(currentRow, offset, length);
+ boolean moreRows = nextRow(currentRow, offset, length);
{code}
So in a normal scan how this will affect? Sorry if I am missing some thing. I
really not getting..:(
{quote}
Also, looking at the patch again, we're not actually filtering rows, but ending
the scan, right?
So the coprocessor hook is misnamed.
{quote}
The hook is for notifying some row is filtered out. This is for the purpose of
doing a fast forward rather than a normal go to next row. So by this fast
forward some time CP implementation can see no more rows remaining in this
region and that is why it returns a boolean to indicate that. If the CP says no
more rows, the scan ends there
> CP hooks in Scan flow for fast forward when filter filters out a row
> --------------------------------------------------------------------
>
> Key: HBASE-5664
> URL: https://issues.apache.org/jira/browse/HBASE-5664
> Project: HBase
> Issue Type: Improvement
> Components: Coprocessors, Filters
> Affects Versions: 0.92.1
> Reporter: Anoop Sam John
> Assignee: Anoop Sam John
> Fix For: 0.96.0, 0.94.5
>
> Attachments: HBASE-5664_94.patch, HBASE-5664_94_V2.patch,
> HBASE-5664_94_V3.patch, HBASE-5664_Trunk.patch, HBASE-5664_Trunk_V2.patch
>
>
> In HRegion.nextInternal(int limit, String metric)
> We have while(true) loop so as to fetch a next result which satisfies
> filter condition. When Filter filters out the current fetched row we call
> nextRow(byte [] currentRow) before going with the next row.
> {code}
> if (results.isEmpty() || filterRow()) {
> // this seems like a redundant step - we already consumed the row
> // there're no left overs.
> // the reasons for calling this method are:
> // 1. reset the filters.
> // 2. provide a hook to fast forward the row (used by subclasses)
> nextRow(currentRow);
> {code}
> // 2. provide a hook to fast forward the row (used by subclasses)
> We can provide same feature of fast forward support for the CP also.
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