Reset compressor between recompression runs

If we reuse the compressor to recompress multiple sets of tuples, internal state gets left behind from the previous run which can contain invalid data. Resetting the compressor first iteration field between runs fixes this.
timescale · Nov 28, 2023 · b2cd1ec · b2cd1ec
1 parent 60e2d88
commit b2cd1ec
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diff --git a/tsl/src/compression/api.c b/tsl/src/compression/api.c
@@ -1500,6 +1500,7 @@ tsl_recompress_chunk_segmentwise(PG_FUNCTION_ARGS)
 
 			tuplesort_performsort(segment_tuplesortstate);
 
+			row_compressor_reset(&row_compressor);
 			recompress_segment(segment_tuplesortstate, uncompressed_chunk_rel, &row_compressor);
 
 			/* now any pointers returned will be garbage */
@@ -1556,6 +1557,7 @@ tsl_recompress_chunk_segmentwise(PG_FUNCTION_ARGS)
 														 uncompressed_chunk_rel,
 														 current_segment);
 		tuplesort_performsort(segment_tuplesortstate);
+		row_compressor_reset(&row_compressor);
 		recompress_segment(segment_tuplesortstate, uncompressed_chunk_rel, &row_compressor);
 		tuplesort_end(segment_tuplesortstate);
 
@@ -1582,6 +1584,7 @@ tsl_recompress_chunk_segmentwise(PG_FUNCTION_ARGS)
 	if (unmatched_rows_exist)
 	{
 		tuplesort_performsort(segment_tuplesortstate);
+		row_compressor_reset(&row_compressor);
 		row_compressor_append_sorted_rows(&row_compressor,
 										  segment_tuplesortstate,
 										  RelationGetDescr(uncompressed_chunk_rel));

diff --git a/tsl/src/compression/compression.c b/tsl/src/compression/compression.c
@@ -1292,6 +1292,12 @@ row_compressor_flush(RowCompressor *row_compressor, CommandId mycid, bool change
 	MemoryContextReset(row_compressor->per_row_ctx);
 }
 
+void
+row_compressor_reset(RowCompressor *row_compressor)
+{
+	row_compressor->first_iteration = true;
+}
+
 void
 row_compressor_finish(RowCompressor *row_compressor)
 {

diff --git a/tsl/src/compression/compression.h b/tsl/src/compression/compression.h
@@ -359,6 +359,7 @@ extern void row_compressor_init(RowCompressor *row_compressor, TupleDesc uncompr
 								const ColumnCompressionInfo **column_compression_info,
 								int16 *column_offsets, int16 num_columns_in_compressed_table,
 								bool need_bistate, bool reset_sequence, int insert_options);
+extern void row_compressor_reset(RowCompressor *row_compressor);
 extern void row_compressor_finish(RowCompressor *row_compressor);
 extern void row_compressor_append_sorted_rows(RowCompressor *row_compressor,
 											  Tuplesortstate *sorted_rel, TupleDesc sorted_desc);