[receiver/mysql] feat: add table size metrics (#32680)

**Description:** This adds table size metrics using the
INFORMATION_SCHEMA TABLES table:
https://dev.mysql.com/doc/refman/8.3/en/information-schema-tables-table.html.
Specifically, we are adding the columns:

`TABLE_ROWS`, `AVG_ROW_LENGTH`, `DATA_LENGTH`, `INDEX_LENGTH`

Link to tracking issue:
#32693

**Testing:** Added testing data, tested locally against MySQL 8.
 
**Documentation:** By default, the metric is turned off. When enabled,
make sure that the MySQL user has access to the tables being monitored.

Author: s-v-a-n

.chloggen/feat_table_stats.yaml

@@ -0,0 +1,30 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: new_component
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: receiver/mysql
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: "Adds INFORMATION_SCHEMA TABLES metrics"
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [32693]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext: |
+  This adds table size metrics using the INFORMATION_SCHEMA TABLES table: https://dev.mysql.com/doc/refman/8.3/en/information-schema-tables-table.html. 
+  Specifically, we are adding the columns: `TABLE_ROWS`, `AVG_ROW_LENGTH`, `DATA_LENGTH`, `INDEX_LENGTH`.
+
+
+# If your change doesn't affect end users or the exported elements of any package,
+# you should instead start your pull request title with [chore] or use the "Skip Changelog" label.
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: []

receiver/mysqlreceiver/client.go

@@ -19,6 +19,7 @@ type client interface {
 	getVersion() (string, error)
 	getGlobalStats() (map[string]string, error)
 	getInnodbStats() (map[string]string, error)
+	getTableStats() ([]TableStats, error)
 	getTableIoWaitsStats() ([]TableIoWaitsStats, error)
 	getIndexIoWaitsStats() ([]IndexIoWaitsStats, error)
 	getStatementEventsStats() ([]StatementEventStats, error)
@@ -57,6 +58,15 @@ type IndexIoWaitsStats struct {
 	index string
 }
 
+type TableStats struct {
+	schema           string
+	name             string
+	rows             int64
+	averageRowLength int64
+	dataLength       int64
+	indexLength      int64
+}
+
 type StatementEventStats struct {
 	schema                    string
 	digest                    string
@@ -231,6 +241,33 @@ func (c *mySQLClient) getInnodbStats() (map[string]string, error) {
 	return query(*c, q)
 }
 
+// getTableStats queries the db for information_schema table size metrics.
+func (c *mySQLClient) getTableStats() ([]TableStats, error) {
+	query := "SELECT TABLE_SCHEMA, TABLE_NAME, TABLE_ROWS, " +
+		"AVG_ROW_LENGTH, DATA_LENGTH, INDEX_LENGTH " +
+		"FROM information_schema.TABLES " +
+		"WHERE TABLE_SCHEMA NOT in ('information_schema', 'sys') " +
+		"ORDER BY TABLE_LENGTH DESC;"
+	rows, err := c.client.Query(query)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	var stats []TableStats
+	for rows.Next() {
+		var s TableStats
+		err := rows.Scan(&s.schema, &s.name,
+			&s.rows, &s.averageRowLength,
+			&s.dataLength, &s.indexLength)
+		if err != nil {
+			return nil, err
+		}
+		stats = append(stats, s)
+	}
+
+	return stats, nil
+}
+
 // getTableIoWaitsStats queries the db for table_io_waits metrics.
 func (c *mySQLClient) getTableIoWaitsStats() ([]TableIoWaitsStats, error) {
 	query := "SELECT OBJECT_SCHEMA, OBJECT_NAME, " +

receiver/mysqlreceiver/documentation.md

@@ -519,6 +519,21 @@ The total wait time of the summarized timed events.
 | digest | Digest. | Any Str |
 | digest_text | Text before digestion. | Any Str |
 
+### mysql.table.average_row_length
+
+The average row length in bytes for a given table.
+
+| Unit | Metric Type | Value Type | Aggregation Temporality | Monotonic |
+| ---- | ----------- | ---------- | ----------------------- | --------- |
+| By | Sum | Int | Cumulative | false |
+
+#### Attributes
+
+| Name | Description | Values |
+| ---- | ----------- | ------ |
+| table | Table name for event or process. | Any Str |
+| schema | The schema of the object. | Any Str |
+
 ### mysql.table.lock_wait.read.count
 
 The total table lock wait read events.
@@ -583,6 +598,37 @@ The total table lock wait write events times.
 | table | Table name for event or process. | Any Str |
 | kind | Write operation types. | Str: ``allow_write``, ``concurrent_insert``, ``low_priority``, ``normal``, ``external`` |
 
+### mysql.table.rows
+
+The number of rows for a given table.
+
+| Unit | Metric Type | Value Type | Aggregation Temporality | Monotonic |
+| ---- | ----------- | ---------- | ----------------------- | --------- |
+| 1 | Sum | Int | Cumulative | false |
+
+#### Attributes
+
+| Name | Description | Values |
+| ---- | ----------- | ------ |
+| table | Table name for event or process. | Any Str |
+| schema | The schema of the object. | Any Str |
+
+### mysql.table.size
+
+The table size in bytes for a given table.
+
+| Unit | Metric Type | Value Type | Aggregation Temporality | Monotonic |
+| ---- | ----------- | ---------- | ----------------------- | --------- |
+| By | Sum | Int | Cumulative | false |
+
+#### Attributes
+
+| Name | Description | Values |
+| ---- | ----------- | ------ |
+| table | Table name for event or process. | Any Str |
+| schema | The schema of the object. | Any Str |
+| kind | The table size types. | Str: ``data``, ``index`` |
+
 ### mysql.table_open_cache
 
 The number of hits, misses or overflows for open tables cache lookups.