# waitforgraph

**Repository Path**: hidva/waitforgraph

## Basic Information

- **Project Name**: waitforgraph
- **Description**: Generate the locks wait-for graph for Greenplum 4.x, 5.x, 6.x, 7.x~
- **Primary Language**: Rust
- **License**: Apache-2.0
- **Default Branch**: master
- **Homepage**: None
- **GVP Project**: No

## Statistics

- **Stars**: 0
- **Forks**: 0
- **Created**: 2022-04-24
- **Last Updated**: 2022-04-24

## Categories & Tags

**Categories**: Uncategorized

**Tags**: greenplum, Lock

## README

A utility used for generating locks wait-for graph for Greenplum Database

```bash
# Use PG* environment variables (PGDATABASE, PGUSER, ...) as connection information by default
waitforgraph > wfg.dot
dot -T svg < wfg.dot > wfg.svg
# also support Connection String described in https://www.postgresql.org/docs/current/libpq-connect.html
waitforgraph dbname=DATABASENAME | dot -T svg > wfg.svg
open wfg.svg
```

```bash
waitforgraph > wfg.dot
# Sometimes we are only interested in one subgraph of the graph.
# And 2018128 is the start point of subgraph.
grep -F -- '->' wft.dot | subgraph 20181218 > wfg.subgraph.dot
dot -T svg < wfg.subgraph.dot > wfg.subgraph.svg
open wfg.subgraph.svg
```

The locks wait-for graph looks as follow:

![gdd.dot](https://raw.githubusercontent.com/hidva/waitforgraph/master/assets/wfg.svg)

There is more detailed information in the dot file:

```dot
strict digraph G {
label="WaitForGraph - Generated By hidva/waitforgraph";
29968;
29970;
29970 -> 29968
}
/*大吉大利~
session 29970 waits for AccessShareLock on locktype=relation,gp_segment_id=-1,database=10902,relation=16395; blocked by session 29968(granted AccessExclusiveLock);
*/
```