PostgreSQL新手求助：Windows客户端查大量数据超时及OOM问题

Hey there! Let's break down why you're hitting timeouts and out-of-memory (OOM) errors with DataGrip on Windows when fetching 16 million rows, while psql on Linux and pgAdmin on Mac work just fine. Here are practical explanations and fixes tailored to your scenario:

First, the root of the issue lies in how each client handles large result sets:

• psql on Linux: When you run SELECT * FROM TABLE;, psql streams results row-by-row directly to the terminal. It never loads the entire 16M rows into memory at once—this is why it finishes in ~10 minutes without hitting OOM.
• DataGrip on Windows: GUI clients like DataGrip default to loading the full result set into RAM to enable UI features like sorting, filtering, or inline editing. 16 million rows can easily consume several gigabytes of memory, which triggers timeouts and OOM errors, especially if your Windows machine's available RAM is constrained.

Try these steps to resolve the issue:

• Enable result streaming:
  Open DataGrip's settings (File > Settings, or press Ctrl+Alt+S), then navigate to Database > Data Views. Look for an option like "Stream results" or "Do not load all results into memory" and enable it. This makes DataGrip handle rows like psql—streaming them instead of storing the entire dataset in RAM.
• Increase DataGrip's heap size:
  If you need to work with the full dataset in the UI, give DataGrip more memory to work with. Locate the datagrip64.exe.vmoptions file (usually in C:\Program Files\JetBrains\DataGrip <your-version>\bin), then modify these lines:

  -Xms2g
  -Xmx8g
  

  Boost the -Xmx value (e.g., to 16g if your Windows machine has enough RAM) to increase the maximum JVM heap allocation for DataGrip.
• Work with smaller subsets first:
  If you don't need every row, use LIMIT to test queries or analyze chunks:

  SELECT * FROM TABLE LIMIT 1000;
  

  For pagination through larger subsets, use OFFSET:

  SELECT * FROM TABLE LIMIT 1000 OFFSET 0;
  SELECT * FROM TABLE LIMIT 1000 OFFSET 1000;
  -- Repeat with increasing OFFSET values
  

• Export directly to file:
  Skip loading results into the UI entirely by using DataGrip's Export Data feature. Run your query, then right-click the result panel (or use the export button) to save the output to a CSV, JSON, or other file format. DataGrip will stream the export without loading all rows into memory, avoiding OOM.

pgAdmin on your MacBook likely has better default streaming settings, or macOS's memory management allocates more flexible resources to GUI apps compared to Windows. If you ever hit limits there, the same streaming and heap adjustment tips above would still apply.

内容的提问来源于stack exchange，提问作者TheSchnitz