#5146
Add histogram metrics into util/metrics.h. The data structure of histogram is implemented in util/histogram.h,
which could also be used in other situations that in need of histogram. Unit tests added as well.
Sometimes we want to detect the hotspot of a cluster, for example, hot scanned tablet, hot wrote tablet,
but we have no insight about tablets in the cluster.
This patch introduce tablet level metrics to help to achieve this object, now support 4 metrics on tablets: `query_scan_bytes `, `query_scan_rows `, `flush_bytes `, `flush_count `.
However, one BE may holds hundreds of thousands of tablets, so I add a parameter for the metrics HTTP request,
and not return tablet level metrics by default.
Sometimes we want to detect the hotspot of a cluster, for example, hot scanned tablet, hot wrote tablet,
but we have no insight about tablets in the cluster.
This patch introduce tablet level metrics to help to achieve this object, now support 4 metrics on tablets: `query_scan_bytes `, `query_scan_rows `, `flush_bytes `, `flush_count `.
However, one BE may holds hundreds of thousands of tablets, so I add a parameter for the metrics HTTP request,
and not return tablet level metrics by default.
Redesign metrics to 3 layers:
MetricRegistry - MetricEntity - Metrics
MetricRegistry : the register center
MetricEntity : the entity registered on MetricRegistry. Generally a MetricRegistry can be registered on several
MetricEntities, each of MetricEntity is an independent entity, such as server, disk_devices, data_directories, thrift
clients and servers, and so on.
Metric : metrics of an entity. Such as fragment_requests_total on server entity, disk_bytes_read on a disk_device entity,
thrift_opened_clients on a thrift_client entity.
MetricPrototype: the type of a metric. MetricPrototype is a global variable, can be shared by the same metrics across
different MetricEntities.
Add a JSON format for existing metrics like this.
```
{
"tags":
{
"metric":"thread_pool",
"name":"thrift-server-pool",
"type":"active_thread_num"
},
"unit":"number",
"value":3
}
```
I add a new JsonMetricVisitor to handle the transformation.
It's not to modify existing PrometheusMetricVisitor and SimpleCoreMetricVisitor.
Also I add
1. A unit item to indicate the metric better
2. Cloning tablet statistics divided by database.
3. Use white space to replace newline in audit.log
Added: Support getting column size and precision info of table or view using JDBC.
Updated: Change the promethues type name GAUGE to lowercase, to fit the latest promethues version.
Updated: Backend ip saved in FE will be compared with BE's local ip when doing heartbeat, to avoid false positive heartbeat response.
Updated: Using version_num of tablet instead of calculating nice value to select cumulative compaction candicates.
Fixed: Predicates should not be pushed down to subquery which contains limit clause.
Fixed: Fix the formula of calculating BE load score.
Fixed: Fix a bug that in some edge cases, non-master Fontend may wait for a unnecessary long timeout after forwarding cmd to Master FE.
Fixed: A bug that granting privs on more than one table does not work.
Fixed: Support 'Insert into' table which contains HLL columns.
Fixed: ExportStmt' toSql() method may throw NullPointer Exception if table does not exist.
Fixed: Remove unnecessary 'get capacity' operation to avoid IO impact.
Internal commit id: merge to c16bd603a53dfe2089ff95704c698a738c317792
