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Pull request overview
This PR optimizes the SQL view v_ahb_diff to improve comparison computation performance by refactoring redundant condition checks and improving the query structure.
- Replaced
CROSS JOINwithJOINto eliminate unnecessary cross products and leverage join optimization - Introduced a
modified_checkCTE to computechanged_columnsonce instead of repeating comparison logic multiple times - Changed from
IFNULL(col, '') != IFNULL(col, '')toIS NOTfor NULL-safe comparisons, which is more efficient
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| -- Pre-compute changed_columns once, derive diff_status from it | ||
| modified_check AS (SELECT TRIM( | ||
| CASE | ||
| WHEN old_tbl.line_ahb_status IS NOT new_tbl.line_ahb_status |
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The comparison uses IS NOT instead of IS DISTINCT FROM. In SQL, IS NOT is used for boolean negation, not for inequality comparison. For NULL-safe inequality, use IS DISTINCT FROM (or in SQLite, the pattern old_tbl.line_ahb_status IS NOT new_tbl.line_ahb_status is invalid syntax). The correct approach is either old_tbl.line_ahb_status != new_tbl.line_ahb_status OR (old_tbl.line_ahb_status IS NULL) != (new_tbl.line_ahb_status IS NULL) or if the SQL dialect supports it, old_tbl.line_ahb_status IS DISTINCT FROM new_tbl.line_ahb_status.
| THEN 'line_ahb_status, ' | ||
| ELSE '' END || | ||
| CASE | ||
| WHEN old_tbl.bedingung IS NOT new_tbl.bedingung |
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The comparison uses IS NOT instead of a proper NULL-safe inequality operator. This is invalid SQL syntax. Use IS DISTINCT FROM if supported by your SQL dialect, or the explicit pattern old_tbl.bedingung != new_tbl.bedingung OR (old_tbl.bedingung IS NULL) != (new_tbl.bedingung IS NULL).
| THEN 'bedingung, ' | ||
| ELSE '' END || | ||
| CASE | ||
| WHEN old_tbl.line_name IS NOT new_tbl.line_name |
There was a problem hiding this comment.
The comparison uses IS NOT instead of a proper NULL-safe inequality operator. This is invalid SQL syntax. Use IS DISTINCT FROM if supported by your SQL dialect, or the explicit pattern old_tbl.line_name != new_tbl.line_name OR (old_tbl.line_name IS NULL) != (new_tbl.line_name IS NULL).
Add comment explaining that SQLite's "IS NOT" operator is equivalent to SQL standard "IS DISTINCT FROM" for NULL-safe comparisons. 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
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