Add AtRev column to only overwrite records with a newer version

cmd/consumer/consumer.go

@@ -10,6 +10,7 @@ import (
 	"net/http"
 	"net/url"
 	"path"
+	"regexp"
 	"strings"
 	"time"
 
@@ -177,6 +178,12 @@ func (c *Consumer) updateCursor(ctx context.Context, seq int64) error {
 
 }
 
+var postgresFixRegexp = regexp.MustCompile(`[^\\](\\\\)*(\\u0000)`)
+
+func escapeNullCharForPostgres(b []byte) []byte {
+	return postgresFixRegexp.ReplaceAll(b, []byte(`$1<0x00>`))
+}
+
 func (c *Consumer) processMessage(ctx context.Context, typ string, r io.Reader, first bool) error {
 	log := zerolog.Ctx(ctx)
 
@@ -253,7 +260,11 @@ func (c *Consumer) processMessage(ctx context.Context, typ string, r io.Reader,
 				Repo:       models.ID(repoInfo.ID),
 				Collection: parts[0],
 				Rkey:       parts[1],
-				Content:    v,
+				// XXX: proper replacement of \u0000 would require full parsing of JSON
+				// and recursive iteration over all string values, but this
+				// should work well enough for now.
+				Content: escapeNullCharForPostgres(v),
+				AtRev:   payload.Rev,
 			})
 		}
 		if len(recs) == 0 && expectRecords {
@@ -261,7 +272,15 @@ func (c *Consumer) processMessage(ctx context.Context, typ string, r io.Reader,
 		}
 		if len(recs) > 0 || expectRecords {
 			err = c.db.Model(&repo.Record{}).
-				Clauses(clause.OnConflict{DoUpdates: clause.AssignmentColumns([]string{"content"}),
+				Clauses(clause.OnConflict{
+					Where: clause.Where{Exprs: []clause.Expression{clause.Or(
+						clause.Eq{Column: clause.Column{Name: "at_rev", Table: "records"}, Value: nil},
+						clause.Eq{Column: clause.Column{Name: "at_rev", Table: "records"}, Value: ""},
+						clause.Lt{
+							Column: clause.Column{Name: "at_rev", Table: "records"},
+							Value:  clause.Column{Name: "at_rev", Table: "excluded"}},
+					)}},
+					DoUpdates: clause.AssignmentColumns([]string{"content", "at_rev"}),
 					Columns:   []clause.Column{{Name: "repo"}, {Name: "collection"}, {Name: "rkey"}}}).
 				Create(recs).Error
 			if err != nil {

cmd/record-indexer/workerpool.go

@@ -5,6 +5,7 @@ import (
 	"context"
 	"fmt"
 	"net/url"
+	"regexp"
 	"strings"
 	"time"
 
@@ -131,6 +132,12 @@ func (p *WorkerPool) worker(ctx context.Context, signal chan struct{}) {
 	}
 }
 
+var postgresFixRegexp = regexp.MustCompile(`[^\\](\\\\)*(\\u0000)`)
+
+func escapeNullCharForPostgres(b []byte) []byte {
+	return postgresFixRegexp.ReplaceAll(b, []byte(`$1<0x00>`))
+}
+
 func (p *WorkerPool) doWork(ctx context.Context, work WorkItem) error {
 	log := zerolog.Ctx(ctx)
 	defer close(work.signal)
@@ -201,18 +208,31 @@ retry:
 			log.Warn().Msgf("Unexpected key format: %q", k)
 			continue
 		}
+		v = regexp.MustCompile(`[^\\](\\\\)*(\\u0000)`).ReplaceAll(v, []byte(`$1<0x00>`))
 		recs = append(recs, repo.Record{
 			Repo:       models.ID(work.Repo.ID),
 			Collection: parts[0],
 			Rkey:       parts[1],
-			Content:    v,
+			// XXX: proper replacement of \u0000 would require full parsing of JSON
+			// and recursive iteration over all string values, but this
+			// should work well enough for now.
+			Content: escapeNullCharForPostgres(v),
+			AtRev:   newRev,
 		})
 	}
 	recordsFetched.Add(float64(len(recs)))
 	if len(recs) > 0 {
 		for _, batch := range splitInBatshes(recs, 500) {
 			result := p.db.Model(&repo.Record{}).
-				Clauses(clause.OnConflict{DoUpdates: clause.AssignmentColumns([]string{"content"}),
+				Clauses(clause.OnConflict{
+					Where: clause.Where{Exprs: []clause.Expression{clause.Or(
+						clause.Eq{Column: clause.Column{Name: "at_rev", Table: "records"}, Value: nil},
+						clause.Eq{Column: clause.Column{Name: "at_rev", Table: "records"}, Value: ""},
+						clause.Lt{
+							Column: clause.Column{Name: "at_rev", Table: "records"},
+							Value:  clause.Column{Name: "at_rev", Table: "excluded"}},
+					)}},
+					DoUpdates: clause.AssignmentColumns([]string{"content", "at_rev"}),
 					Columns:   []clause.Column{{Name: "repo"}, {Name: "collection"}, {Name: "rkey"}}}).
 				Create(batch)
 			if err := result.Error; err != nil {
@@ -229,6 +249,9 @@ retry:
 		return fmt.Errorf("updating repo rev: %w", err)
 	}
 
+	// TODO: check for records that are missing in the repo download
+	// and mark them as deleted.
+
 	return nil
 }
 

repo/repo.go

@@ -34,9 +34,10 @@ type Record struct {
 	ID         models.ID `gorm:"primarykey"`
 	CreatedAt  time.Time
 	UpdatedAt  time.Time
-	Repo       models.ID       `gorm:"index:idx_repo_record_key,unique,priority:1;not null"`
+	Repo       models.ID       `gorm:"index:idx_repo_record_key,unique,priority:1;not null;index:idx_repo_rev"`
 	Collection string          `gorm:"index:idx_repo_record_key,unique,priority:2;not null"`
 	Rkey       string          `gorm:"index:idx_repo_record_key,unique,priority:3"`
+	AtRev      string          `gorm:"index:idx_repo_rev"`
 	Content    json.RawMessage `gorm:"type:JSONB"`
 	Deleted    bool
 }