siddharthteotia commented on code in PR #9454:
URL: https://github.com/apache/pinot/pull/9454#discussion_r983122859
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pinot-segment-local/src/test/java/org/apache/pinot/segment/local/segment/index/loader/SegmentPreProcessorTest.java:
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@@ -304,6 +306,28 @@ public void testEnableFSTIndexOnExistingColumnDictEncoded()
checkFSTIndexCreation(EXISTING_STRING_COL_DICT, 9, 4,
_newColumnsSchemaWithFST, false, false, 26);
}
+ @Test
+ public void testForwardIndexHandler()
+ throws Exception {
+ Map<String, ChunkCompressionType> compressionConfigs = new HashMap<>();
+ ChunkCompressionType newCompressionType = ChunkCompressionType.ZSTANDARD;
+ compressionConfigs.put(EXISTING_STRING_COL_RAW, newCompressionType);
+ _indexLoadingConfig.setCompressionConfigs(compressionConfigs);
+ _indexLoadingConfig.setNoDictionaryColumns(new HashSet<String>() {{
+ add(EXISTING_STRING_COL_RAW);
+ }});
+
+ // Test1: Rewriting forward index will be a no-op for v1 segments. Default
LZ4 compressionType will be retained.
+ constructV1Segment();
+ checkForwardIndexCreation(EXISTING_STRING_COL_RAW, 5, 3, _schema, false,
false, false, 0, ChunkCompressionType.LZ4);
+
+ // Convert the segment to V3.
+ new SegmentV1V2ToV3FormatConverter().convert(_indexDir);
+
+ // Test2: Now forward index will be rewritten with ZSTANDARD
compressionType.
Review Comment:
So one concern (and please clarify if this is a non-issue) I had was for the
scenario I asked for in first point
Once the ForwardIndexHandler finishes rewriting fwd index with new comp
codec and we return
- the new fwd index is in v3 format
- the entry for old fwd index is removed from in-memory map
- the index_map file has 2 entries for fwd index on that column (old and new)
Next handler (RangeIndexHandler in this case) gets invoked and reads the
forward index to generate range index. I am guessing this will read the new
forward index (because old one is no longer accessible via the _columnEntries
map).
Basically, my concern was if the range index gets generated incorrectly /
corrupt because of 2 forward indexes (since sweep hasn't been done as of this
time). But looks like this can't happen
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