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Implementation of function progress_bar.
Additional tools for tracking the progress of the running query: * function progress_bar(pid), which returns a numeric from 0 to 1, characterizing the number of processed rows in relation to their planned number. * function progress_bar_visual(pid, delay), which displays this numeric with a delay of several seconds. Developers: Ekaterina Sokolova Vyacheslav Makarov
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‎README.md

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@@ -308,3 +308,117 @@ Do not hesitate to post your issues, questions and new ideas at the [issues](htt
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## Authors
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[Maksim Milyutin](https://github.com/maksm90)
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Alexey Kondratov <[email protected]> Postgres Professional Ltd., Russia
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## Function progress\_bar
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```plpgsql
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progress_bar(
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integer pid
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) returns FLOAT
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```
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extracts the current query state from backend with specified 'pid'. Then gets the numerical values of the actual rows and total rows and count progress for the whole query tree. Function returns numeric value from 0 to 1 describing the measure of query fulfillment. If there is no information about current state of the query, or the impossibility of counting, the corresponding messages will be displayed.
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## Function progress\_bar\_visual
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```plpgsql
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progress_bar(
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integer pid,
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integer delay
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) returns VOID
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```
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cyclically extracts and print the current query state in numeric value from backend with specified 'pid' every period specified by 'delay' in seconds. This is the looping version of the progress\_bar function that returns void value.
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**_Warning_**: Calling role have to be superuser or member of the role whose backend is being called. Otherwise function prints ERROR message `permission denied`.
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## Examples
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Assume first backend executes some function:
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```sql
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postgres=# insert into table_name select generate_series(1,10000000);
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```
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Other backend can get the follow output:
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```sql
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postgres=# SELECT pid FROM pg_stat_activity where query like 'insert%';
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pid
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-------
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23877
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(1 row)
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postgres=# SELECT progress_bar(23877);
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progress_bar
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--------------
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0.6087927
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(1 row)
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```
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Or continuous version:
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```sql
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postgres=# SELECT progress_bar_visual(23877, 1);
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Progress = 0.043510
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Progress = 0.085242
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Progress = 0.124921
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Progress = 0.168168
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Progress = 0.213803
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Progress = 0.250362
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Progress = 0.292632
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Progress = 0.331454
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Progress = 0.367509
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Progress = 0.407450
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Progress = 0.448646
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Progress = 0.488171
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Progress = 0.530559
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Progress = 0.565558
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Progress = 0.608039
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Progress = 0.645778
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Progress = 0.654842
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Progress = 0.699006
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Progress = 0.735760
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Progress = 0.787641
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Progress = 0.832160
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Progress = 0.871077
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Progress = 0.911858
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Progress = 0.956362
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Progress = 0.995097
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Progress = 1.000000
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progress_bar_visual
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---------------------
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1
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(1 row)
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```
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Also uncountable queries exist. Assume first backend executes some function:
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```sql
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DELETE from table_name;
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```
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Other backend can get the follow output:
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```sql
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postgres=# SELECT pid FROM pg_stat_activity where query like 'delete%';
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pid
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-------
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23877
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(1 row)
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postgres=# SELECT progress_bar(23877);
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INFO: Counting Progress doesn't available
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progress_bar
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--------------
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-1
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(1 row)
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postgres=# SELECT progress_bar_visual(23877, 5);
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INFO: Counting Progress doesn't available
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progress_bar_visual
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---------------------
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-1
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(1 row)
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```
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## Reinstallation
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If you already have a module 'pg_query_state' without progress bar functions installed, execute this in the module's directory:
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```
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make install USE_PGXS=1
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```
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It is essential to restart the PostgreSQL instance. After that, execute the following queries in psql:
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```sql
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DROP EXTENSION IF EXISTS pg_query_state;
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CREATE EXTENSION pg_query_state;
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```
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## Authors
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Ekaterina Sokolova <[email protected]> Postgres Professional Ltd., Russia
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Vyacheslav Makarov <[email protected]> Postgres Professional Ltd., Russia

‎init.sql

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@@ -15,3 +15,14 @@ CREATE FUNCTION pg_query_state(pid integer
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, leader_pid integer)
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AS 'MODULE_PATHNAME'
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LANGUAGE C STRICT VOLATILE;
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CREATE FUNCTION progress_bar(pid integer)
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RETURNS FLOAT
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AS 'MODULE_PATHNAME'
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LANGUAGE C STRICT VOLATILE;
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CREATE FUNCTION progress_bar_visual(pid integer
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, delay integer = 1)
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RETURNS FLOAT
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AS 'MODULE_PATHNAME', 'progress_bar'
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LANGUAGE C STRICT VOLATILE;

‎pg_query_state.c

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ereport(LOG, (errcode(ERRCODE_INTERNAL_ERROR),
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errmsg("pg_query_state peer is not responding")));
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}
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/*
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* Count progress of query execution like ratio of
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* number of received to planned rows in persent.
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* Changes of this function can lead to more plausible results.
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*/
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static double
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CountProgress(char *plan_text)
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{
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char *plan; /* Copy of plan_text */
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char *node; /* Part of plan with information about single node */
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char *rows; /* Pointer to rows */
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char *actual_rows_str; /* Actual rows in string format */
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char *plan_rows_str; /* Planned rows in string format */
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int len; /* Length of rows in string format */
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double actual_rows; /* Actual rows */
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double plan_rows; /* Planned rows */
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double progress = 0; /* Summary progress on nodes */
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int node_amount = 0; /* Amount of plantree nodes using in counting progress */
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plan = palloc(sizeof(char) * (strlen(plan_text) + 1));
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strcpy(plan, plan_text);
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node = strtok(plan, "["); /* Get information about upper node */
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while (node != NULL)
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{
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if (strstr(node, "Seq Scan") == NULL)
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{
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if (strstr(node, "ModifyTable") == NULL)
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{
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if (strstr(node, "Result") == NULL)
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{
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if ((rows = strstr(node, "Rows Removed by Filter")) != NULL)
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{
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/*
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* Filter node have 2 conditions:
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* 1) Was not filtered (current progress = 0)
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* 2) Was filtered (current progress = 1)
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*/
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node_amount++;
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plan_rows = 1;
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rows = (char *) (rows + strlen("Rows Removed by Filter\": ") * sizeof(char));
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if (rows[0] == '0')
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actual_rows = 0;
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else
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actual_rows = 1;
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} else if ((rows = strstr(node, "\"Actual Rows\": ")) != NULL)
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{
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node_amount++;
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actual_rows = 0;
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plan_rows = 0;
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rows = (char *) (rows + strlen("\"Actual Rows\": ") * sizeof(char));
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len = strstr(rows, "\n") - rows;
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if ((strstr(rows, ",") - rows) < len)
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len = strstr(rows, ",") - rows;
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actual_rows_str = palloc(sizeof(char) * (len + 1));
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actual_rows_str[len] = 0;
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strncpy(actual_rows_str, rows, len);
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actual_rows = strtod(actual_rows_str, NULL);
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pfree(actual_rows_str);
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rows = strstr(node, "\"Plan Rows\": ");
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rows = (char *) (rows + strlen("\"Plan Rows\": ") * sizeof(char));
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len = strstr(rows, ",") - rows;
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plan_rows_str = palloc(sizeof(char) * (len + 1));
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plan_rows_str[len] = 0;
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strncpy(plan_rows_str, rows, len);
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plan_rows = strtod(plan_rows_str, NULL);
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pfree(plan_rows_str);
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if (plan_rows > actual_rows)
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progress += actual_rows / plan_rows;
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else
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progress += 1;
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}
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}
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}
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}
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node = strtok(NULL, "[");
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}
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pfree(plan);
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if (node_amount > 0)
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{
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progress = progress / node_amount;
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if (progress == 1)
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progress = 0.999999;
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}
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else
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return -1;
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return progress;
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}
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static double
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GetCurrentNumericState(shm_mq_msg *msg)
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{
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typedef struct
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{
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PGPROC *proc;
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ListCell *frame_cursor;
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int frame_index;
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List *stack;
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} proc_state;
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/* multicall context type */
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typedef struct
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{
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ListCell *proc_cursor;
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List *procs;
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} pg_qs_fctx;
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pg_qs_fctx *fctx;
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List *qs_stack;
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proc_state *p_state;
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stack_frame *frame;
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char *plan_text;
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fctx = (pg_qs_fctx *) palloc(sizeof(pg_qs_fctx));
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fctx->procs = NIL;
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p_state = (proc_state *) palloc(sizeof(proc_state));
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qs_stack = deserialize_stack(msg->stack, msg->stack_depth);
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p_state->proc = msg->proc;
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p_state->stack = qs_stack;
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p_state->frame_index = 0;
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p_state->frame_cursor = list_head(qs_stack);
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fctx->procs = lappend(fctx->procs, p_state);
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fctx->proc_cursor = list_head(fctx->procs);
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frame = (stack_frame *) lfirst(p_state->frame_cursor);
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plan_text = frame->plan->vl_dat;
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return CountProgress(plan_text);
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}
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PG_FUNCTION_INFO_V1(progress_bar);
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Datum
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progress_bar(PG_FUNCTION_ARGS)
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{
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pid_t pid = PG_GETARG_INT32(0);
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int delay = 0;
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PGPROC *proc;
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Oid counterpart_user_id;
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shm_mq_msg *msg;
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List *bg_worker_procs = NIL;
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List *msgs;
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double progress;
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double old_progress;
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if (PG_NARGS() == 2)
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{
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/*
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* This is continuous mode, function 'progress_bar_visual',
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* we need to get delay value.
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*/
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delay = PG_GETARG_INT32(1);
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if (delay < 1)
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ereport(ERROR, (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
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errmsg("the value of \"delay\" must be positive integer")));
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}
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if (!module_initialized)
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ereport(ERROR, (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
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errmsg("pg_query_state wasn't initialized yet")));
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if (pid == MyProcPid)
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ereport(ERROR, (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
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errmsg("attempt to extract state of current process")));
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proc = BackendPidGetProc(pid);
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if (!proc || proc->backendId == InvalidBackendId || proc->databaseId == InvalidOid || proc->roleId == InvalidOid)
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ereport(ERROR, (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
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errmsg("backend with pid=%d not found", pid)));
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counterpart_user_id = GetRemoteBackendUserId(proc);
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if (!(superuser() || GetUserId() == counterpart_user_id))
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ereport(ERROR, (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
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errmsg("permission denied")));
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old_progress = 0;
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progress = 0;
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bg_worker_procs = GetRemoteBackendWorkers(proc);
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msgs = GetRemoteBackendQueryStates(proc,
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bg_worker_procs,
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0, 1, 0, 0, 0,
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EXPLAIN_FORMAT_JSON);
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if (list_length(msgs) == 0)
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elog(WARNING, "backend does not reply");
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msg = (shm_mq_msg *) linitial(msgs);
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switch (msg->result_code)
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{
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case QUERY_NOT_RUNNING:
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elog(INFO, "query not runing");
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PG_RETURN_FLOAT8((float8) -1);
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break;
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case STAT_DISABLED:
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elog(INFO, "query execution statistics disabled");
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PG_RETURN_FLOAT8((float8) -1);
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default:
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break;
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}
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if (msg->result_code == QS_RETURNED && delay == 0)
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{
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progress = GetCurrentNumericState(msg);
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if (progress < 0)
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{
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elog(INFO, "Counting Progress doesn't available");
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PG_RETURN_FLOAT8((float8) -1);
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}
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else
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PG_RETURN_FLOAT8((float8) progress);
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}
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else if (msg->result_code == QS_RETURNED)
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{
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while (msg->result_code == QS_RETURNED)
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{
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progress = GetCurrentNumericState(msg);
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if (progress > old_progress)
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{
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elog(INFO, "\rProgress = %f", progress);
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old_progress = progress;
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}
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else if (progress < 0)
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{
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elog(INFO, "Counting Progress doesn't available");
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break;
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}
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for (int i = 0; i < delay; i++)
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{
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pg_usleep(1000000);
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CHECK_FOR_INTERRUPTS();
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}
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bg_worker_procs = GetRemoteBackendWorkers(proc);
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msgs = GetRemoteBackendQueryStates(proc,
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bg_worker_procs,
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0, 1, 0, 0, 0,
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EXPLAIN_FORMAT_JSON);
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if (list_length(msgs) == 0)
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elog(WARNING, "backend does not reply");
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msg = (shm_mq_msg *) linitial(msgs);
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}
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if (progress > -1)
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elog(INFO, "\rProgress = 1.000000");
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PG_RETURN_FLOAT8((float8) 1);
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}
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PG_RETURN_FLOAT8((float8) -1);
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}

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