Misthios/grafana-zabbix
1
0
Fork 0
Code Issues Pull Requests Actions 1 Packages Projects Releases Wiki Activity

docs: update db connection docs

Browse Source
This commit is contained in:
Alexander Zobnin
2017-10-22 11:06:48 +03:00
parent c8205b30c3
commit 538589b99b
4 changed files with 56 additions and 11 deletions
Download Patch File Download Diff File Expand all files Collapse all files

48
docs/sources/reference/direct-db-connection.md
View File

@@ -22,12 +22,26 @@ and `trend.get` API calls.
Below is an example query for getting history in the Grafana-Zabbix Plugin:
**MySQL**:
```sql
SELECT itemid AS metric, clock AS time_sec, {aggFunc}(value) as value
FROM {historyTable}
WHERE itemid IN ({itemids})
AND clock > {timeFrom} AND clock < {timeTill}
GROUP BY time_sec DIV {intervalSec}, metric
FROM {historyTable}
WHERE itemid IN ({itemids})
AND clock > {timeFrom} AND clock < {timeTill}
GROUP BY time_sec DIV {intervalSec}, metric
ORDER BY time_sec ASC
```
**PostgreSQL**:
```sql
SELECT to_char(itemid, 'FM99999999999999999999') AS metric,
clock / {intervalSec} * {intervalSec} AS time,
{aggFunc}(value) AS value
FROM {historyTable}
WHERE itemid IN ({itemids})
AND clock > {timeFrom} AND clock < {timeTill}
GROUP BY 1, 2
ORDER BY time ASC
```
where `{aggFunc}` is one of `[AVG, MIN, MAX, SUM, COUNT]` aggregation functions, `{historyTable}` is a history table,
@@ -36,18 +50,34 @@ where `{aggFunc}` is one of `[AVG, MIN, MAX, SUM, COUNT]` aggregation functions,
When getting trends, the plugin additionally queries a particular value column (`value_avg`, `value_min` or `value_max`) which
depends on `consolidateBy` function value:
**MySQL**:
```sql
SELECT itemid AS metric, clock AS time_sec, {aggFunc}({valueColumn}) as value
FROM {trendsTable}
WHERE itemid IN ({itemids})
AND clock > {timeFrom} AND clock < {timeTill}
GROUP BY time_sec DIV {intervalSec}, metric
FROM {trendsTable}
WHERE itemid IN ({itemids})
AND clock > {timeFrom} AND clock < {timeTill}
GROUP BY time_sec DIV {intervalSec}, metric
ORDER BY time_sec ASC
```
**PostgreSQL**:
```sql
SELECT to_char(itemid, 'FM99999999999999999999') AS metric,
clock / {intervalSec} * {intervalSec} AS time,
{aggFunc}({valueColumn}) AS value
FROM {trendsTable}
WHERE itemid IN ({itemids})
AND clock > {timeFrom} AND clock < {timeTill}
GROUP BY 1, 2
ORDER BY time ASC
```
**Note**: these queries may be changed in future, so look into sources for actual query structure.
As you can see, the Grafana-Zabbix plugin uses aggregation by a given time interval. This interval is provided by Grafana and depends on the panel width in pixels. Thus, Grafana displays the data in the proper resolution.
## Functions usage with Direct DB Connection
There's only one function that directly affects the backend data. This function is `consolidateBy`. Other functions work on the client side and transform data that comes from the backend. So you should clearly understand that this is pre-aggregated data (by AVG, MAX, MIN, etc).
For example, say you want to group values by 1 hour interval and `max` function. If you just apply `groupBy(10m, max)` function, your result will be wrong, because you would transform data aggregated by default `AVG` function. You should use `consolidateBy(max)` coupled with `groupBy(10m, max)` in order to get a precise result.
For example, say you want to group values by 1 hour interval and `max` function. If you just apply `groupBy(10m, max)` function, your result will be wrong, because you would transform data aggregated by default `AVG` function. You should use `consolidateBy(max)` coupled with `groupBy(10m, max)` in order to get a precise result.