Add setting

src/Core/Settings.h

@@ -176,6 +176,7 @@ class IColumn;
     M(LogQueriesType, log_queries_min_type, QueryLogElementType::QUERY_START, "Minimal type in query_log to log, possible values (from low to high): QUERY_START, QUERY_FINISH, EXCEPTION_BEFORE_START, EXCEPTION_WHILE_PROCESSING.", 0) \
     M(Milliseconds, log_queries_min_query_duration_ms, 0, "Minimal time for the query to run, to get to the query_log/query_thread_log/query_views_log.", 0) \
     M(UInt64, log_queries_cut_to_length, 100000, "If query length is greater than specified threshold (in bytes), then cut query when writing to query log. Also limit length of printed query in ordinary text log.", 0) \
+    M(Float, log_queries_probability, 1., "Log queries with the specified probabality.", 0) \
     \
     M(DistributedProductMode, distributed_product_mode, DistributedProductMode::DENY, "How are distributed subqueries performed inside IN or JOIN sections?", IMPORTANT) \
     \

src/Interpreters/executeQuery.cpp

@@ -56,6 +56,8 @@
 #include <Processors/Formats/IOutputFormat.h>
 #include <Processors/Sources/SinkToOutputStream.h>
 
+#include <random>
+
 
 namespace ProfileEvents
 {
@@ -659,6 +661,11 @@ static std::tuple<ASTPtr, BlockIO> executeQueryImpl(
 
             elem.client_info = client_info;
 
+            std::bernoulli_distribution should_write_log{
+                            settings.log_queries_probability};
+
+            context->setSetting("log_queries", should_write_log(thread_local_rng));
+
             bool log_queries = settings.log_queries && !internal;
 
             /// Log into system table start of query execution, if need.