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https://issues.apache.org/jira/browse/HBASE-17678?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16040507#comment-16040507
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Anoop Sam John commented on HBASE-17678:
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CellUtil#createCell will again make a new KV which internally having another
copy of the already copied component. We can avoid that.
Better to use KeyValueUtil#toNewKeyCell(final Cell cell)
For every return value of the individual filters we need the extra check on
what to pass next to this Cell? May be some specific return values only. Iff
we store? Other cases just add a comment why we dont need that and just set as
null? I hope even if prevCell is null the remaining logic will work.
So only very specific cases we have this prevCell keeping and so the extra
copy. This is per cell that is why worried much. WDYT [~tedyu]?
> FilterList with MUST_PASS_ONE may lead to redundant cells returned
> ------------------------------------------------------------------
>
> Key: HBASE-17678
> URL: https://issues.apache.org/jira/browse/HBASE-17678
> Project: HBase
> Issue Type: Bug
> Components: Filters
> Affects Versions: 2.0.0, 1.3.0, 1.2.1
> Environment: RedHat 7.x
> Reporter: Jason Tokayer
> Assignee: Zheng Hu
> Attachments: HBASE-17678.addendum.patch, HBASE-17678.v1.patch,
> HBASE-17678.v1.rough.patch, HBASE-17678.v2.patch, HBASE-17678.v3.patch,
> HBASE-17678.v4.patch, HBASE-17678.v4.patch, HBASE-17678.v5.patch,
> HBASE-17678.v6.patch, HBASE-17678.v7.patch, HBASE-17678.v7.patch,
> TestColumnPaginationFilterDemo.java
>
>
> When combining ColumnPaginationFilter with a single-element filterList,
> MUST_PASS_ONE and MUST_PASS_ALL give different results when there are
> multiple cells with the same timestamp. This is unexpected since there is
> only a single filter in the list, and I would believe that MUST_PASS_ALL and
> MUST_PASS_ONE should only affect the behavior of the joined filter and not
> the behavior of any one of the individual filters. If this is not a bug then
> it would be nice if the documentation is updated to explain this nuanced
> behavior.
> I know that there was a decision made in an earlier Hbase version to keep
> multiple cells with the same timestamp. This is generally fine but presents
> an issue when using the aforementioned filter combination.
> Steps to reproduce:
> In the shell create a table and insert some data:
> {code:none}
> create 'ns:tbl',{NAME => 'family',VERSIONS => 100}
> put 'ns:tbl','row','family:name','John',1000000000000
> put 'ns:tbl','row','family:name','Jane',1000000000000
> put 'ns:tbl','row','family:name','Gil',1000000000000
> put 'ns:tbl','row','family:name','Jane',1000000000000
> {code}
> Then, use a Scala client as:
> {code:none}
> import org.apache.hadoop.hbase.filter._
> import org.apache.hadoop.hbase.util.Bytes
> import org.apache.hadoop.hbase.client._
> import org.apache.hadoop.hbase.{CellUtil, HBaseConfiguration, TableName}
> import scala.collection.mutable._
> val config = HBaseConfiguration.create()
> config.set("hbase.zookeeper.quorum", "localhost")
> config.set("hbase.zookeeper.property.clientPort", "2181")
> val connection = ConnectionFactory.createConnection(config)
> val logicalOp = FilterList.Operator.MUST_PASS_ONE
> val limit = 1
> var resultsList = ListBuffer[String]()
> for (offset <- 0 to 20 by limit) {
> val table = connection.getTable(TableName.valueOf("ns:tbl"))
> val paginationFilter = new ColumnPaginationFilter(limit,offset)
> val filterList: FilterList = new FilterList(logicalOp,paginationFilter)
> println("@ filterList = "+filterList)
> val results = table.get(new
> Get(Bytes.toBytes("row")).setFilter(filterList))
> val cells = results.rawCells()
> if (cells != null) {
> for (cell <- cells) {
> val value = new String(CellUtil.cloneValue(cell))
> val qualifier = new String(CellUtil.cloneQualifier(cell))
> val family = new String(CellUtil.cloneFamily(cell))
> val result = "OFFSET = "+offset+":"+family + "," + qualifier
> + "," + value + "," + cell.getTimestamp()
> resultsList.append(result)
> }
> }
> }
> resultsList.foreach(println)
> {code}
> Here are the results for different limit and logicalOp settings:
> {code:none}
> Limit = 1 & logicalOp = MUST_PASS_ALL:
> scala> resultsList.foreach(println)
> OFFSET = 0:family,name,Jane,1000000000000
> Limit = 1 & logicalOp = MUST_PASS_ONE:
> scala> resultsList.foreach(println)
> OFFSET = 0:family,name,Jane,1000000000000
> OFFSET = 1:family,name,Gil,1000000000000
> OFFSET = 2:family,name,Jane,1000000000000
> OFFSET = 3:family,name,John,1000000000000
> Limit = 2 & logicalOp = MUST_PASS_ALL:
> scala> resultsList.foreach(println)
> OFFSET = 0:family,name,Jane,1000000000000
> Limit = 2 & logicalOp = MUST_PASS_ONE:
> scala> resultsList.foreach(println)
> OFFSET = 0:family,name,Jane,1000000000000
> OFFSET = 2:family,name,Jane,1000000000000
> {code}
> So, it seems that MUST_PASS_ALL gives the expected behavior, but
> MUST_PASS_ONE does not. Furthermore, MUST_PASS_ONE seems to give only a
> single (not-duplicated) within a page, but not across pages.
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