Fix segfault after column drop on compressed table

CHANGELOG.md

@@ -30,6 +30,7 @@ accidentally triggering the load of a previous DB version.**
 * #5499 Do not segfault on large histogram() parameters
 * #5497 Allow named time_bucket arguments in Cagg definition
 * #5500 Fix when no FROM clause in continuous aggregate definition
+* #5462 Fix segfault after column drop on compressed table
 
 **Thanks**
 * @nikolaps for reporting an issue with the COPY fetcher

tsl/src/nodes/decompress_chunk/exec.c

@@ -473,7 +473,7 @@ decompress_chunk_create_tuple(DecompressChunkState *state)
 
 		if (!state->initialized)
 		{
-			ExecClearTuple(decompressed_slot);
+			ExecStoreAllNullTuple(decompressed_slot);
 
 			/*
 			 * Reset expression memory context to clean out any cruft from

tsl/test/expected/compression_errors.out

@@ -630,3 +630,33 @@ INSERT INTO ts_table SELECT * FROM data_table;
 --cleanup tables
 DROP TABLE data_table cascade;
 DROP TABLE ts_table cascade;
+--invalid reads for row expressions after column dropped on compressed tables #5458
+CREATE TABLE readings(
+    "time"  TIMESTAMPTZ NOT NULL,
+    battery_status  TEXT,
+    battery_temperature  DOUBLE PRECISION
+);
+INSERT INTO readings ("time") VALUES ('2022-11-11 11:11:11-00');
+SELECT create_hypertable('readings', 'time', chunk_time_interval => interval '12 hour', migrate_data=>true);
+NOTICE:  migrating data to chunks
+   create_hypertable    
+------------------------
+ (35,public,readings,t)
+(1 row)
+
+ALTER TABLE readings SET (timescaledb.compress,timescaledb.compress_segmentby = 'battery_temperature');
+SELECT compress_chunk(show_chunks('readings'));
+              compress_chunk              
+------------------------------------------
+ _timescaledb_internal._hyper_35_22_chunk
+(1 row)
+
+ALTER TABLE readings DROP COLUMN battery_status;
+INSERT INTO readings ("time", battery_temperature) VALUES ('2022-11-11 11:11:11', 0.2);
+SELECT readings FROM readings;
+               readings               
+--------------------------------------
+ ("Fri Nov 11 03:11:11 2022 PST",)
+ ("Fri Nov 11 11:11:11 2022 PST",0.2)
+(2 rows)
+

tsl/test/sql/compression_errors.sql

@@ -364,3 +364,21 @@ INSERT INTO ts_table SELECT * FROM data_table;
 --cleanup tables
 DROP TABLE data_table cascade;
 DROP TABLE ts_table cascade;
+
+--invalid reads for row expressions after column dropped on compressed tables #5458
+CREATE TABLE readings(
+    "time"  TIMESTAMPTZ NOT NULL,
+    battery_status  TEXT,
+    battery_temperature  DOUBLE PRECISION
+);
+
+INSERT INTO readings ("time") VALUES ('2022-11-11 11:11:11-00');
+
+SELECT create_hypertable('readings', 'time', chunk_time_interval => interval '12 hour', migrate_data=>true);
+
+ALTER TABLE readings SET (timescaledb.compress,timescaledb.compress_segmentby = 'battery_temperature');
+SELECT compress_chunk(show_chunks('readings'));
+
+ALTER TABLE readings DROP COLUMN battery_status;
+INSERT INTO readings ("time", battery_temperature) VALUES ('2022-11-11 11:11:11', 0.2);
+SELECT readings FROM readings;