Readur/migrations/20250628000001_backfill_ocr...

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-- Backfill OCR confidence scores for existing documents
-- Since OCR confidence was previously hardcoded to 85%, we need to recalculate
-- actual confidence for documents that currently have this placeholder value
-- First, let's identify documents that likely have placeholder confidence
-- (85% exactly, which was the hardcoded value)
CREATE TEMP TABLE documents_to_update AS
SELECT id, ocr_text, ocr_status
FROM documents
WHERE ocr_confidence = 85.0
AND ocr_status = 'completed'
AND ocr_text IS NOT NULL
AND length(trim(ocr_text)) > 0;
-- For now, we'll estimate confidence based on text quality metrics
-- This is a rough approximation until we can re-run OCR with actual confidence
UPDATE documents
SET ocr_confidence = CASE
-- High quality text: good length, reasonable character distribution
WHEN length(trim(ocr_text)) > 1000
AND (length(ocr_text) - length(replace(replace(ocr_text, ' ', ''), chr(10), ''))) * 100.0 / length(ocr_text) > 10.0 -- > 10% whitespace
AND length(replace(replace(replace(ocr_text, ' ', ''), chr(10), ''), chr(13), '')) * 100.0 / length(ocr_text) > 70.0 -- > 70% non-whitespace chars
THEN 90.0 + (random() * 8.0) -- 90-98%
-- Medium quality text: decent length, some structure
WHEN length(trim(ocr_text)) > 100
AND (length(ocr_text) - length(replace(replace(ocr_text, ' ', ''), chr(10), ''))) * 100.0 / length(ocr_text) > 5.0 -- > 5% whitespace
AND length(replace(replace(replace(ocr_text, ' ', ''), chr(10), ''), chr(13), '')) * 100.0 / length(ocr_text) > 50.0 -- > 50% non-whitespace chars
THEN 70.0 + (random() * 15.0) -- 70-85%
-- Low quality text: short or poor structure
WHEN length(trim(ocr_text)) > 10
AND length(replace(replace(replace(ocr_text, ' ', ''), chr(10), ''), chr(13), '')) * 100.0 / length(ocr_text) > 30.0 -- > 30% non-whitespace chars
THEN 40.0 + (random() * 25.0) -- 40-65%
-- Very poor quality: very short or mostly garbage
ELSE 20.0 + (random() * 15.0) -- 20-35%
END
WHERE id IN (SELECT id FROM documents_to_update);
-- Add a comment explaining what we did
COMMENT ON COLUMN documents.ocr_confidence IS 'OCR confidence percentage (0-100). Values may be estimated for documents processed before real confidence calculation was implemented.';
-- Log the update
DO $$
DECLARE
updated_count INTEGER;
BEGIN
SELECT COUNT(*) INTO updated_count FROM documents_to_update;
RAISE NOTICE 'Backfilled OCR confidence for % documents that had placeholder 85%% confidence', updated_count;
END $$;
-- Clean up
DROP TABLE documents_to_update;
-- Create an index to help with confidence-based queries
CREATE INDEX IF NOT EXISTS idx_documents_ocr_confidence_range
ON documents(ocr_confidence)
WHERE ocr_confidence IS NOT NULL;