Database Tool laggy and freeze

I was able to capture the following in the Activity Monitor right after the UI became responsive again:

%CPU Subsystem

158.9 <Process total CPU usage>
45.9 editor.impl.view (in com.intellij.openapi)
36.9 editor.impl (in com.intellij.openapi)
8.6 editor.ex.util (in com.intellij.openapi)
4.8 it.unimi.dsi.fastutil.ints
2.3 <unidentified: DefaultDispatcher-worker->
1.5 <Activity Monitor>
1.2 platform.core.nio.fs (in com.intellij)

Hello, @G1ZgY,

To check the issue, please create YouTrack ticket and attach the logs archive, which can be found under Help | Collect Logs and Diagnostic Data.

Problem description:

I am experiencing severe UI freezes in PyCharm Database Tools when working with a specific MySQL table containing JSON columns.

Environment:

• MySQL database
• PyCharm Professional (Database Tools plugin)
• Same behavior across multiple servers containing the same database/schema
• Other tables work normally

Table structure:

• Several numeric columns
• Timestamp column
• Two JSON columns

Observed behavior:

• Selecting rows from this table freezes the IDE UI for a long time
• Even fetching a small number of rows may cause the UI to hang
• Query execution on the MySQL side appears fast, but rendering/display in PyCharm becomes extremely slow
• The issue started recently; previously the same table worked normally

Investigation results:

• Queries excluding the problematic JSON column work fast
• Queries using truncated/casted JSON values work fast
• Queries selecting the raw JSON column cause severe freezes

This strongly suggests the issue is related to PyCharm/DataGrip JSON rendering/parsing rather than MySQL execution itself.

Additional findings:

• MySQL server performance appears normal
• LIMIT queries with small result sets are enough to reproduce the issue
• The problem reproduces only in PyCharm Database Tools
• The same data works correctly when JSON is converted to plain text or truncated before rendering

Example reproduction pattern:

SELECT
id,
created_at,
json_column
FROM some_table
ORDER BY id DESC
LIMIT 20;

Workaround that avoids freezes:

SELECT
id,
created_at,
LEFT(CAST(json_column AS CHAR), 1000) AS json_preview
FROM some_table
ORDER BY id DESC
LIMIT 20;

Hypothesis:
PyCharm/DataGrip may be performing expensive synchronous JSON parsing/rendering/tree-building for MySQL native JSON columns, causing UI thread freezes.

Could you please investigate possible regressions in JSON rendering/editor behavior in recent versions?

Hi G1ZgY, M9icokat,

I remember replying to both of your YouTrack tickets, so I assume you’re no longer experiencing this issue.

As a note in case someone else encounters this issue, the problem was fixed in DBE-25765, and the fix is included in IDE version 2026.1.1.