Handle max parameter size

pg_tracing.max_parameter_size GUC parameter was present but never used. Use it to apply possibly truncate string stored in the parameter buffer shared across a traced transaction.
DataDog · Aug 22, 2024 · 9ffce21 · 9ffce21
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diff --git a/Makefile b/Makefile
@@ -27,11 +27,11 @@ OBJS = \
 	src/pg_tracing_strinfo.o \
 	src/version_compat.o
 
-REGRESSCHECKS = setup utility select insert trigger cursor json transaction
+REGRESSCHECKS = setup utility select parameters insert trigger cursor json transaction
 ifeq ($(PG_VERSION),15)
 REGRESSCHECKS += trigger_15
 else
-REGRESSCHECKS += extended trigger_16
+REGRESSCHECKS += extended trigger_16 parameters_16
 endif
 REGRESSCHECKS += sample planstate planstate_bitmap planstate_hash \
 				 planstate_projectset planstate_subplans planstate_union \

diff --git a/doc/pg_tracing.md b/doc/pg_tracing.md
@@ -189,10 +189,6 @@ Controls the fraction of statements that generate spans. Statements with traceco
 
 Controls the fraction of statements with SQLCommenter tracecontext and an enabled sampled flag that will generate spans. The default value is 1.
 
-### pg_tracing.export_parameters (boolean)
-
-Controls whether the query's parameters should be exported in spans metadata. The default value is `on`.
-
 ### pg_tracing.otel_endpoint (string)
 
 URL of the otel collector to send spans to. Example: 'http://127.0.0.1:4318/v1/traces'. This parameter can only be set at server start. The default value is NULL.

diff --git a/expected/parameters.out b/expected/parameters.out
@@ -0,0 +1,167 @@
+-- Check that parameters are not exported when disabled
+SET pg_tracing.max_parameter_size=0;
+/*traceparent='00-00000000000000000000000000000001-0000000000000001-01'*/ select 1, 2, 3;
+ ?column? | ?column? | ?column? 
+----------+----------+----------
+        1 |        2 |        3
+(1 row)
+
+SELECT span_operation, parameters, lvl from peek_ordered_spans where trace_id='00000000000000000000000000000001';
+   span_operation   | parameters | lvl 
+--------------------+------------+-----
+ select $1, $2, $3; |            |   1
+ Planner            |            |   2
+ ExecutorRun        |            |   2
+ Result             |            |   3
+(4 rows)
+
+-- Saturate the parameter buffer
+SET pg_tracing.max_parameter_size=1;
+/*traceparent='00-00000000000000000000000000000002-0000000000000002-01'*/ select 1, 2, 3;
+ ?column? | ?column? | ?column? 
+----------+----------+----------
+        1 |        2 |        3
+(1 row)
+
+SELECT span_operation, parameters, lvl from peek_ordered_spans where trace_id='00000000000000000000000000000002';
+   span_operation   | parameters  | lvl 
+--------------------+-------------+-----
+ select $1, $2, $3; | {1,...,...} |   1
+ Planner            |             |   2
+ ExecutorRun        |             |   2
+ Result             |             |   3
+(4 rows)
+
+SET pg_tracing.max_parameter_size=2;
+/*traceparent='00-00000000000000000000000000000003-0000000000000003-01'*/ select 1, 2, 3;
+ ?column? | ?column? | ?column? 
+----------+----------+----------
+        1 |        2 |        3
+(1 row)
+
+SELECT span_operation, parameters, lvl from peek_ordered_spans where trace_id='00000000000000000000000000000003';
+   span_operation   | parameters  | lvl 
+--------------------+-------------+-----
+ select $1, $2, $3; | {1,...,...} |   1
+ Planner            |             |   2
+ ExecutorRun        |             |   2
+ Result             |             |   3
+(4 rows)
+
+SET pg_tracing.max_parameter_size=3;
+/*traceparent='00-00000000000000000000000000000004-0000000000000004-01'*/ select 1, 2, 3;
+ ?column? | ?column? | ?column? 
+----------+----------+----------
+        1 |        2 |        3
+(1 row)
+
+SELECT span_operation, parameters, lvl from peek_ordered_spans where trace_id='00000000000000000000000000000004';
+   span_operation   | parameters | lvl 
+--------------------+------------+-----
+ select $1, $2, $3; | {1,2,...}  |   1
+ Planner            |            |   2
+ ExecutorRun        |            |   2
+ Result             |            |   3
+(4 rows)
+
+SET pg_tracing.max_parameter_size=4;
+/*traceparent='00-00000000000000000000000000000005-0000000000000005-01'*/ select 1, 2, 3;
+ ?column? | ?column? | ?column? 
+----------+----------+----------
+        1 |        2 |        3
+(1 row)
+
+SELECT span_operation, parameters, lvl from peek_ordered_spans where trace_id='00000000000000000000000000000005';
+   span_operation   | parameters | lvl 
+--------------------+------------+-----
+ select $1, $2, $3; | {1,2,...}  |   1
+ Planner            |            |   2
+ ExecutorRun        |            |   2
+ Result             |            |   3
+(4 rows)
+
+SET pg_tracing.max_parameter_size=5;
+/*traceparent='00-00000000000000000000000000000006-0000000000000006-01'*/ select 1, 2, 3;
+ ?column? | ?column? | ?column? 
+----------+----------+----------
+        1 |        2 |        3
+(1 row)
+
+SELECT span_operation, parameters, lvl from peek_ordered_spans where trace_id='00000000000000000000000000000006';
+   span_operation   | parameters | lvl 
+--------------------+------------+-----
+ select $1, $2, $3; | {1,2,3}    |   1
+ Planner            |            |   2
+ ExecutorRun        |            |   2
+ Result             |            |   3
+(4 rows)
+
+CALL clean_spans();
+-- Test truncated string
+SET pg_tracing.max_parameter_size=2;
+/*traceparent='00-00000000000000000000000000000001-0000000000000001-01'*/ select 'testtruncatedstring';
+      ?column?       
+---------------------
+ testtruncatedstring
+(1 row)
+
+SELECT span_operation, parameters, lvl from peek_ordered_spans where trace_id='00000000000000000000000000000001';
+ span_operation | parameters | lvl 
+----------------+------------+-----
+ select $1;     | {'t...}    |   1
+ Planner        |            |   2
+ ExecutorRun    |            |   2
+ Result         |            |   3
+(4 rows)
+
+SET pg_tracing.max_parameter_size=19;
+/*traceparent='00-00000000000000000000000000000002-0000000000000002-01'*/ select 'testtruncatedstring';
+      ?column?       
+---------------------
+ testtruncatedstring
+(1 row)
+
+SELECT span_operation, parameters, lvl from peek_ordered_spans where trace_id='00000000000000000000000000000002';
+ span_operation |        parameters        | lvl 
+----------------+--------------------------+-----
+ select $1;     | {'testtruncatedstrin...} |   1
+ Planner        |                          |   2
+ ExecutorRun    |                          |   2
+ Result         |                          |   3
+(4 rows)
+
+SET pg_tracing.max_parameter_size=20;
+/*traceparent='00-00000000000000000000000000000003-0000000000000003-01'*/ select 'testtruncatedstring';
+      ?column?       
+---------------------
+ testtruncatedstring
+(1 row)
+
+SELECT span_operation, parameters, lvl from peek_ordered_spans where trace_id='00000000000000000000000000000003';
+ span_operation |        parameters         | lvl 
+----------------+---------------------------+-----
+ select $1;     | {'testtruncatedstring...} |   1
+ Planner        |                           |   2
+ ExecutorRun    |                           |   2
+ Result         |                           |   3
+(4 rows)
+
+SET pg_tracing.max_parameter_size=21;
+/*traceparent='00-00000000000000000000000000000004-0000000000000004-01'*/ select 'testtruncatedstring';
+      ?column?       
+---------------------
+ testtruncatedstring
+(1 row)
+
+SELECT span_operation, parameters, lvl from peek_ordered_spans where trace_id='00000000000000000000000000000004';
+ span_operation |       parameters        | lvl 
+----------------+-------------------------+-----
+ select $1;     | {'testtruncatedstring'} |   1
+ Planner        |                         |   2
+ ExecutorRun    |                         |   2
+ Result         |                         |   3
+(4 rows)
+
+-- Cleanup
+CALL clean_spans();
+CALL reset_settings();
diff --git a/expected/parameters_16.out b/expected/parameters_16.out
@@ -0,0 +1,52 @@
+-- Saturate the parameter buffer with extended protocol
+SET pg_tracing.max_parameter_size=1;
+/*traceparent='00-00000000000000000000000000000001-0000000000000001-01'*/ select $1, $2, $3 \bind 1 2 3 \g
+ ?column? | ?column? | ?column? 
+----------+----------+----------
+ 1        | 2        | 3
+(1 row)
+
+SELECT span_operation, parameters, lvl from peek_ordered_spans where trace_id='00000000000000000000000000000001';
+  span_operation   | parameters  | lvl 
+-------------------+-------------+-----
+ select $1, $2, $3 | {1,...,...} |   1
+ Planner           |             |   2
+ ExecutorRun       |             |   2
+ Result            |             |   3
+(4 rows)
+
+SET pg_tracing.max_parameter_size=2;
+/*traceparent='00-00000000000000000000000000000002-0000000000000002-01'*/ select $1, $2, $3 \bind 1 2 3 \g
+ ?column? | ?column? | ?column? 
+----------+----------+----------
+ 1        | 2        | 3
+(1 row)
+
+SELECT span_operation, parameters, lvl from peek_ordered_spans where trace_id='00000000000000000000000000000002';
+  span_operation   | parameters  | lvl 
+-------------------+-------------+-----
+ select $1, $2, $3 | {1,...,...} |   1
+ Planner           |             |   2
+ ExecutorRun       |             |   2
+ Result            |             |   3
+(4 rows)
+
+SET pg_tracing.max_parameter_size=3;
+/*traceparent='00-00000000000000000000000000000003-0000000000000003-01'*/ select $1, $2, $3 \bind 1 2 3 \g
+ ?column? | ?column? | ?column? 
+----------+----------+----------
+ 1        | 2        | 3
+(1 row)
+
+SELECT span_operation, parameters, lvl from peek_ordered_spans where trace_id='00000000000000000000000000000003';
+  span_operation   | parameters | lvl 
+-------------------+------------+-----
+ select $1, $2, $3 | {1,2,...}  |   1
+ Planner           |            |   2
+ ExecutorRun       |            |   2
+ Result            |            |   3
+(4 rows)
+
+-- Cleanup
+CALL clean_spans();
+CALL reset_settings();
diff --git a/expected/select.out b/expected/select.out
@@ -172,24 +172,6 @@ SELECT span_operation, parameters, lvl from peek_ordered_spans where trace_id='0
  Result         |            |   3
 (4 rows)
 
--- Check that parameters are not exported when disabled
-SET pg_tracing.export_parameters=false;
-/*dddbs='postgres.db',traceparent='00-0000000000000000000000000000000d-000000000000000d-01'*/ select 1, 2, 3;
- ?column? | ?column? | ?column? 
-----------+----------+----------
-        1 |        2 |        3
-(1 row)
-
-SELECT span_operation, parameters, lvl from peek_ordered_spans where trace_id='0000000000000000000000000000000d';
-   span_operation   | parameters | lvl 
---------------------+------------+-----
- select $1, $2, $3; |            |   1
- Planner            |            |   2
- ExecutorRun        |            |   2
- Result             |            |   3
-(4 rows)
-
-SET pg_tracing.export_parameters=true;
 -- Check multi statement query
 CALL clean_spans();
 SET pg_tracing.sample_rate = 1.0;

diff --git a/expected/setup.out b/expected/setup.out
@@ -16,6 +16,7 @@ AS $$
     SET pg_tracing.sample_rate TO DEFAULT;
     SET pg_tracing.caller_sample_rate TO DEFAULT;
     SET pg_tracing.track_utility TO DEFAULT;
+    SET pg_tracing.max_parameter_size TO DEFAULT;
 $$;
 CREATE OR REPLACE PROCEDURE reset_pg_tracing_test_table() AS $$
 BEGIN

diff --git a/sql/parameters.sql b/sql/parameters.sql
@@ -0,0 +1,47 @@
+-- Check that parameters are not exported when disabled
+SET pg_tracing.max_parameter_size=0;
+/*traceparent='00-00000000000000000000000000000001-0000000000000001-01'*/ select 1, 2, 3;
+SELECT span_operation, parameters, lvl from peek_ordered_spans where trace_id='00000000000000000000000000000001';
+
+-- Saturate the parameter buffer
+SET pg_tracing.max_parameter_size=1;
+/*traceparent='00-00000000000000000000000000000002-0000000000000002-01'*/ select 1, 2, 3;
+SELECT span_operation, parameters, lvl from peek_ordered_spans where trace_id='00000000000000000000000000000002';
+
+SET pg_tracing.max_parameter_size=2;
+/*traceparent='00-00000000000000000000000000000003-0000000000000003-01'*/ select 1, 2, 3;
+SELECT span_operation, parameters, lvl from peek_ordered_spans where trace_id='00000000000000000000000000000003';
+
+SET pg_tracing.max_parameter_size=3;
+/*traceparent='00-00000000000000000000000000000004-0000000000000004-01'*/ select 1, 2, 3;
+SELECT span_operation, parameters, lvl from peek_ordered_spans where trace_id='00000000000000000000000000000004';
+
+SET pg_tracing.max_parameter_size=4;
+/*traceparent='00-00000000000000000000000000000005-0000000000000005-01'*/ select 1, 2, 3;
+SELECT span_operation, parameters, lvl from peek_ordered_spans where trace_id='00000000000000000000000000000005';
+
+SET pg_tracing.max_parameter_size=5;
+/*traceparent='00-00000000000000000000000000000006-0000000000000006-01'*/ select 1, 2, 3;
+SELECT span_operation, parameters, lvl from peek_ordered_spans where trace_id='00000000000000000000000000000006';
+CALL clean_spans();
+
+-- Test truncated string
+SET pg_tracing.max_parameter_size=2;
+/*traceparent='00-00000000000000000000000000000001-0000000000000001-01'*/ select 'testtruncatedstring';
+SELECT span_operation, parameters, lvl from peek_ordered_spans where trace_id='00000000000000000000000000000001';
+
+SET pg_tracing.max_parameter_size=19;
+/*traceparent='00-00000000000000000000000000000002-0000000000000002-01'*/ select 'testtruncatedstring';
+SELECT span_operation, parameters, lvl from peek_ordered_spans where trace_id='00000000000000000000000000000002';
+
+SET pg_tracing.max_parameter_size=20;
+/*traceparent='00-00000000000000000000000000000003-0000000000000003-01'*/ select 'testtruncatedstring';
+SELECT span_operation, parameters, lvl from peek_ordered_spans where trace_id='00000000000000000000000000000003';
+
+SET pg_tracing.max_parameter_size=21;
+/*traceparent='00-00000000000000000000000000000004-0000000000000004-01'*/ select 'testtruncatedstring';
+SELECT span_operation, parameters, lvl from peek_ordered_spans where trace_id='00000000000000000000000000000004';
+
+-- Cleanup
+CALL clean_spans();
+CALL reset_settings();
diff --git a/sql/parameters_16.sql b/sql/parameters_16.sql
@@ -0,0 +1,16 @@
+-- Saturate the parameter buffer with extended protocol
+SET pg_tracing.max_parameter_size=1;
+/*traceparent='00-00000000000000000000000000000001-0000000000000001-01'*/ select $1, $2, $3 \bind 1 2 3 \g
+SELECT span_operation, parameters, lvl from peek_ordered_spans where trace_id='00000000000000000000000000000001';
+
+SET pg_tracing.max_parameter_size=2;
+/*traceparent='00-00000000000000000000000000000002-0000000000000002-01'*/ select $1, $2, $3 \bind 1 2 3 \g
+SELECT span_operation, parameters, lvl from peek_ordered_spans where trace_id='00000000000000000000000000000002';
+
+SET pg_tracing.max_parameter_size=3;
+/*traceparent='00-00000000000000000000000000000003-0000000000000003-01'*/ select $1, $2, $3 \bind 1 2 3 \g
+SELECT span_operation, parameters, lvl from peek_ordered_spans where trace_id='00000000000000000000000000000003';
+
+-- Cleanup
+CALL clean_spans();
+CALL reset_settings();
diff --git a/sql/select.sql b/sql/select.sql
@@ -64,12 +64,6 @@ SELECT span_operation, parameters, lvl from peek_ordered_spans where trace_id='0
 /*dddbs='postgres.db',traceparent='00-0000000000000000000000000000000c-000000000000000c-01'*/ select 1; select 2;
 SELECT span_operation, parameters, lvl from peek_ordered_spans where trace_id='0000000000000000000000000000000c';
 
--- Check that parameters are not exported when disabled
-SET pg_tracing.export_parameters=false;
-/*dddbs='postgres.db',traceparent='00-0000000000000000000000000000000d-000000000000000d-01'*/ select 1, 2, 3;
-SELECT span_operation, parameters, lvl from peek_ordered_spans where trace_id='0000000000000000000000000000000d';
-SET pg_tracing.export_parameters=true;
-
 -- Check multi statement query
 CALL clean_spans();
 SET pg_tracing.sample_rate = 1.0;

diff --git a/sql/setup.sql b/sql/setup.sql
@@ -18,6 +18,7 @@ AS $$
     SET pg_tracing.sample_rate TO DEFAULT;
     SET pg_tracing.caller_sample_rate TO DEFAULT;
     SET pg_tracing.track_utility TO DEFAULT;
+    SET pg_tracing.max_parameter_size TO DEFAULT;
 $$;
 
 CREATE OR REPLACE PROCEDURE reset_pg_tracing_test_table() AS $$