Add :client_id automatic variable for custom pgbench scripts.

This makes it easier to write custom scripts that have different logic for
each client.

Gurjeet Singh, with some changes by me.

diff --git a/contrib/pgbench/pgbench.c b/contrib/pgbench/pgbench.c
index 8c202bf8702d26f2f1efe4b529b1ebd6a814068b..1303217086e7878291dc3c96630733d959a683a0 100644 (file)
--- a/contrib/pgbench/pgbench.c
+++ b/contrib/pgbench/pgbench.c
@@ -2544,6 +2544,20 @@ main(int argc, char **argv)
        }
    }
 
+   /*
+    * Define a :client_id variable that is unique per connection. But don't
+    * override an explicit -D switch.
+    */
+   if (getVariable(&state[0], "client_id") == NULL)
+   {
+       for (i = 0; i < nclients; i++)
+       {
+           snprintf(val, sizeof(val), "%d", i);
+           if (!putVariable(&state[i], "startup", "client_id", val))
+               exit(1);
+       }
+   }
+
    if (!is_no_vacuum)
    {
        fprintf(stderr, "starting vacuum...");

diff --git a/doc/src/sgml/pgbench.sgml b/doc/src/sgml/pgbench.sgml
index e9900d326701173f5ee979db9e18cb9b3c537d62..8775606affaeb2a20c9eda2b1cafa3a0e38f1681 100644 (file)
--- a/doc/src/sgml/pgbench.sgml
+++ b/doc/src/sgml/pgbench.sgml
@@ -600,13 +600,39 @@ pgbench  options  dbname
    Variables can be set by the command-line -D option,
    explained above, or by the meta commands explained below.
    In addition to any variables preset by -D command-line options,
-   the variable scale is preset to the current scale factor.
+   there are a few variables that are preset automatically, listed in
+   . A value specified for these
+   variables using -D takes precedence over the automatic presets.
    Once set, a variable's
    value can be inserted into a SQL command by writing
    :variablename.  When running more than
    one client session, each session has its own set of variables.
   
 
+   
+    Automatic variables
+    
+     
+      
+       Variable
+       Description
+      
+     
+
+     
+      
+        scale 
+       current scale factor
+      
+
+      
+        client_id 
+       unique number identifying the client session (starts from zero)
+      
+     
+    
+   
+
   
    Script file meta commands begin with a backslash (\).
    Arguments to a meta command are separated by white space.