samof76 · September 14, 2024 03:47 · Sep 14, 2024
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+To investigate high RAM usage in ClickHouse and determine what's consuming so much memory, you can try the following steps:
+
+1. Check system tables:
+   Query the system.metrics and system.asynchronous_metrics tables to get an overview of memory usage:
+
+   ```sql
+   SELECT * FROM system.metrics WHERE metric LIKE '%Memory%';
+   SELECT * FROM system.asynchronous_metrics WHERE metric LIKE '%Memory%';
+   ```
+
+2. Examine query memory usage:
+   Look at currently running queries and their memory consumption:
+
+   ```sql
+   SELECT query_id, user, elapsed, memory_usage
+   FROM system.processes
+   ORDER BY memory_usage DESC;
+   ```
+
+3. Check table sizes:
+   Identify large tables that might be causing memory pressure:
+
+   ```sql
+   SELECT database, name, total_bytes, total_rows
+   FROM system.tables
+   ORDER BY total_bytes DESC
+   LIMIT 10;
+   ```
+
+4. Review merge processes:
+   Check if there are any large merges in progress:
+
+   ```sql
+   SELECT * FROM system.merges;
+   ```
+
+5. Inspect background processes:
+   Look at background processes that might be consuming memory:
+
+   ```sql
+   SELECT * FROM system.background_processing_pool;
+   ```
+
+
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