[HBASE-10965] Automate detection of presence of Filter#filterRow()

• Type: Task
• Status: Closed
• Priority: Major
• Resolution: Won't Fix
• Component/s: Filters
• Assignee: Unassigned
• Reporter: Ted Yu
• Created: 11/Apr/14 21:25
• Updated: 17/Jun/22 05:31
• Resolved: 12/Mar/17 03:16

Description

There is potential inconsistency between the return value of Filter#hasFilterRow() and presence of Filter#filterRow().

Filters may override Filter#filterRow() while leaving return value of Filter#hasFilterRow() being false (inherited from FilterBase).

Downside to purely depending on hasFilterRow() telling us whether custom filter overrides filterRow(List) or filterRow() is that the check below may be rendered ineffective:

          if (nextKv == KV_LIMIT) {
            if (this.filter != null && filter.hasFilterRow()) {
              throw new IncompatibleFilterException(
                "Filter whose hasFilterRow() returns true is incompatible with scan with limit!");
            }

When user forgets to override hasFilterRow(), the above check becomes not useful.

Another limitation is that we cannot optimize FilterList#filterRow() through short circuit when FilterList#hasFilterRow() turns false.
See https://issues.apache.org/jira/browse/HBASE-11093?focusedCommentId=13985149&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-13985149

This JIRA aims to remove the inconsistency by automatically detecting the presence of overridden Filter#filterRow(). For FilterBase-derived classes, if filterRow() is implemented and not inherited from FilterBase, it is equivalent to having hasFilterRow() return true.

With precise detection of presence of Filter#filterRow(), the following code from HRegion is no longer needed while backward compatibility is kept.

      return filter != null && (!filter.hasFilterRow())
          && filter.filterRow();

Issue Links

• blocks: HBASE-11093 FilterList#filterRow() iterates through its filters even though FilterList#hasFilterRow() returns false