A CPV code is now stored once, keeping its longest description

internal/store/README.md

@@ -36,7 +36,7 @@ internal/store/common.go           common for migrate, store and direct access
 | `opportunity_marks` | `uuid` | `uuid` references `opportunities`. The user's own marks (`hidden`, `skipped`, `interested`, `bid_submitted`, `won`, `lost`), each `BOOLEAN NOT NULL DEFAULT 0`. A `CHECK` constraint stops `won` and `lost` both being set. |
 | `opportunity_releases` | (`uuid`, `release_id`) | Write-once. `uuid` references `opportunities`. `data` is TEXT, so `json_extract` works on it. |
 | `opportunity_release_tags` | (`uuid`, `release_id`, `tag`) | Write-once. (`uuid`, `release_id`) references `opportunity_releases`. |
-| `classification_codes` | `id` | Shared between opportunities. A row is reused only when every content column matches. The table grows over time to include codes not already seen in fetched opportunities. |
+| `classification_codes` | `id` | Shared between opportunities. A CPV code has one row (unique on `code` where `is_cpv`), keeping the longest description it has been given: EU Supply cuts descriptions to 64 characters. A code of any other scheme gets a row per distinct content. The table grows over time to include codes not already seen in fetched opportunities. |
 | `opportunity_classifications` | (`opportunity_uuid`, `classification_id`) | Mapping table; replaced as a set when the opportunity is updated. |
 | `opportunities_fts` | rowid = `opportunities.id` | FTS5 index on `opportunities.title`, kept in sync by triggers. |
 | `opportunity_change_batches` | `id`; `hash` (unique) | Write-once. One row per save that adds opportunities or gives them new releases, and per change of marks. `hash` names the batch to clients (random, so unguessable); `created_at` orders the batches. |
@@ -44,7 +44,7 @@ internal/store/common.go           common for migrate, store and direct access
 
 Foreign keys are enforced (`_foreign_keys=on` in the connection string) and cascade on delete from `opportunities`. The connection also enables WAL mode, a 5s busy timeout, and `_txlock=immediate`, so a save takes the write lock up front rather than failing halfway through.
 
-**When adding a classification scheme flag** (e.g. `is_unspsc`), the migration adding the column must drop and recreate the `classification_codes_content` unique index with the new column included. Otherwise rows differing only by that flag would be merged.
+**When adding a classification scheme flag** (e.g. `is_unspsc`), the migration adding the column must drop and recreate the `classification_codes_content` unique index with the new column included. Otherwise rows differing only by that flag would be merged. A scheme whose codes have one official description, like CPV, can instead have a partial unique index on `code` (as `classification_codes_cpv` does), with its own `ON CONFLICT` clause in `upsertClassificationCodeReturningID`.
 
 **internal/types**: The structs contain `db` tags to allow sqlx to map table columns to struct members. Any struct members not mapped to a column (including child slices) are referenced by `db:"-"`.
 

internal/store/migrate_test.go

@@ -327,3 +327,78 @@ func TestFailedMigrationIsRolledBack(t *testing.T) {
 		t.Errorf("failed migration left %d objects behind", indexes)
 	}
 }
+
+// Migration 10 merges each CPV code's rows into the one with the longest
+// description, moving the links to it (one link if an opportunity had both),
+// and leaves other schemes' rows alone.
+func TestMigration10MergesCPVDuplicates(t *testing.T) {
+	ctx := context.Background()
+	m, db := newMigrator(t)
+	if _, err := m.UpTo(ctx, 9); err != nil {
+		t.Fatal(err)
+	}
+
+	const full = "Petroleum products, fuel, electricity and other sources of energy"
+	setup := []string{
+		`INSERT INTO opportunities (uuid, uuid_type, title, status, latest_release_date)
+		 VALUES ('a', 'ocid', 'A', 'active', '2026-10-01'),
+		        ('b', 'ocid', 'B', 'active', '2026-10-01')`,
+		`INSERT INTO classification_codes (id, is_cpv, code, classification) VALUES
+		 (1, 1, '09000000', '` + full + `'),
+		 (2, 1, '09000000', '` + full[:64] + `'),
+		 (3, 0, '123', 'Scheme X'),
+		 (4, 0, '123', 'Scheme X, amended')`,
+		// a links to both CPV rows, b only to the cut one.
+		`INSERT INTO opportunity_classifications VALUES
+		 ('a', 1), ('a', 2), ('b', 2), ('a', 3), ('b', 4)`,
+	}
+	for _, statement := range setup {
+		if _, err := db.ExecContext(ctx, statement); err != nil {
+			t.Fatal(err)
+		}
+	}
+
+	if _, err := m.UpTo(ctx, 10); err != nil {
+		t.Fatal(err)
+	}
+
+	var codes []string
+	rows, err := db.QueryContext(ctx,
+		`SELECT id || ':' || classification FROM classification_codes ORDER BY id`)
+	if err != nil {
+		t.Fatal(err)
+	}
+	for rows.Next() {
+		var code string
+		rows.Scan(&code)
+		codes = append(codes, code)
+	}
+	rows.Close()
+	want := "1:" + full + "|3:Scheme X|4:Scheme X, amended"
+	if got := strings.Join(codes, "|"); got != want {
+		t.Errorf("codes = %s; want %s", got, want)
+	}
+
+	var links []string
+	rows, err = db.QueryContext(ctx, `SELECT opportunity_uuid || classification_id
+		FROM opportunity_classifications ORDER BY 1`)
+	if err != nil {
+		t.Fatal(err)
+	}
+	for rows.Next() {
+		var link string
+		rows.Scan(&link)
+		links = append(links, link)
+	}
+	rows.Close()
+	if got := strings.Join(links, ","); got != "a1,a3,b1,b4" {
+		t.Errorf("links = %s; want a1,a3,b1,b4", got)
+	}
+
+	// A second row for the code is now refused.
+	_, err = db.ExecContext(ctx, `INSERT INTO classification_codes
+		(is_cpv, code, classification) VALUES (1, '09000000', 'Other')`)
+	if err == nil {
+		t.Error("a second row for a CPV code was accepted")
+	}
+}

internal/store/migrations/00010_unique_cpv_codes.sql

@@ -0,0 +1,60 @@
+-- +goose Up
+-- +goose StatementBegin
+-- A CPV code has one official description, so it is now one row whatever
+-- description it arrives with: EU Supply cuts descriptions to 64 characters,
+-- which made a second row for each code it sent. The duplicates are merged
+-- into the row with the longest description, and the upsert keeps the
+-- longest from now on. Other schemes still get a row per distinct content.
+
+-- The row each CPV row merges into.
+CREATE TEMP TABLE "cpv_merge" AS
+SELECT
+	"c"."id" AS "id",
+	(
+		SELECT "k"."id" FROM "classification_codes" "k"
+		WHERE "k"."is_cpv" AND "k"."code" = "c"."code"
+		ORDER BY length("k"."classification") DESC, "k"."id"
+		LIMIT 1
+	) AS "keep_id"
+FROM "classification_codes" "c"
+WHERE "c"."is_cpv";
+
+-- An opportunity linked to both rows keeps only its link to the kept one.
+DELETE FROM "opportunity_classifications"
+WHERE "classification_id" IN (
+	SELECT "id" FROM "cpv_merge" WHERE "id" <> "keep_id"
+)
+AND EXISTS (
+	SELECT 1
+	FROM "cpv_merge" "m"
+	JOIN "opportunity_classifications" "kept"
+		ON "kept"."classification_id" = "m"."keep_id"
+	WHERE "m"."id" = "opportunity_classifications"."classification_id"
+		AND "kept"."opportunity_uuid"
+			= "opportunity_classifications"."opportunity_uuid"
+);
+
+UPDATE "opportunity_classifications"
+SET "classification_id" = (
+	SELECT "keep_id" FROM "cpv_merge"
+	WHERE "id" = "opportunity_classifications"."classification_id"
+)
+WHERE "classification_id" IN (
+	SELECT "id" FROM "cpv_merge" WHERE "id" <> "keep_id"
+);
+
+DELETE FROM "classification_codes"
+WHERE "id" IN (SELECT "id" FROM "cpv_merge" WHERE "id" <> "keep_id");
+
+DROP TABLE "cpv_merge";
+
+CREATE UNIQUE INDEX IF NOT EXISTS "classification_codes_cpv"
+	ON "classification_codes" ("code") WHERE "is_cpv";
+-- +goose StatementEnd
+
+-- +goose Down
+-- +goose StatementBegin
+-- The merged duplicates aren't restored: they only differed by a cut-off
+-- description.
+DROP INDEX IF EXISTS "classification_codes_cpv";
+-- +goose StatementEnd

internal/store/queries.go

@@ -197,15 +197,24 @@ ORDER BY release_id, tag`
 
 // ---------- classification_codes ----------
 
-// upsertClassificationCodeReturningID returns the id of the row matching
-// every content column, inserting it first if needed. Named parameters
+// upsertClassificationCodeReturningID returns the id of the row for a
+// classification, inserting it first if needed. Named parameters
 // (types.ClassificationCode).
 //
-// The no-op DO UPDATE (rather than DO NOTHING) makes RETURNING yield the
-// existing row's id on conflict.
+// A CPV code has one row whatever its description (migration 00010): the
+// row keeps the longest description it has been given, as EU Supply cuts
+// them to 64 characters. Any other scheme's row matches every content
+// column. The no-op DO UPDATE (rather than DO NOTHING) makes RETURNING
+// yield the existing row's id on conflict.
 const upsertClassificationCodeReturningID = `
 INSERT INTO classification_codes (is_cpv, code, classification)
 VALUES (:is_cpv, :code, :classification)
+ON CONFLICT (code) WHERE is_cpv
+	DO UPDATE SET classification = CASE
+		WHEN length(excluded.classification) > length(classification)
+			THEN excluded.classification
+		ELSE classification
+	END
 ON CONFLICT (is_cpv, code, classification)
 	DO UPDATE SET is_cpv = excluded.is_cpv
 RETURNING id`

internal/store/store_test.go

@@ -3,6 +3,7 @@ package store_test
 import (
 	"context"
 	"errors"
+	"fmt"
 	"path/filepath"
 	"slices"
 	"strings"
@@ -273,8 +274,9 @@ func TestNewerReleaseUpdatesOpportunityAndSearchIndex(t *testing.T) {
 		got.Classifications[0].Classification != "IT services (amended)" {
 		t.Fatalf("classifications not replaced: %+v", got.Classifications)
 	}
-	if got.Classifications[0].ID == oldIT {
-		t.Errorf("changed description should create a new classification row")
+	// A CPV code is one row: the longer description replaces the shorter.
+	if got.Classifications[0].ID != oldIT {
+		t.Errorf("a CPV code's new description should keep its row")
 	}
 
 	for title, want := range map[string]int{"cloud": 0, "redesign": 1} {
@@ -295,6 +297,61 @@ func TestNewerReleaseUpdatesOpportunityAndSearchIndex(t *testing.T) {
 	}
 }
 
+// A CPV code keeps one row and its longest description, whichever order
+// the descriptions arrive in (EU Supply cuts them to 64 characters); a code
+// of another scheme still gets a row per description.
+func TestCPVCodeKeepsLongestDescription(t *testing.T) {
+	const full = "Petroleum products, fuel, electricity and other sources of energy"
+	cut := full[:64]
+	for name, order := range map[string][]string{
+		"full first": {full, cut},
+		"cut first":  {cut, full},
+	} {
+		t.Run(name, func(t *testing.T) {
+			s := openStore(t)
+			var ids []int64
+			for i, description := range order {
+				o := opportunity(fmt.Sprintf("ocds-%d", i), "Fuel", 1, "r1")
+				o.Classifications = []types.ClassificationCode{
+					{
+						IsCPV:          true,
+						Code:           "09000000",
+						Classification: description,
+					},
+				}
+				mustSave(t, s, o)
+				ids = append(ids, o.Classifications[0].ID)
+			}
+			if ids[0] != ids[1] {
+				t.Errorf("ids = %v; want one row for the code", ids)
+			}
+			for _, uuid := range []string{"ocds-0", "ocds-1"} {
+				got := mustGet(t, s, uuid).Classifications[0].Classification
+				if got != full {
+					t.Errorf("%s: description = %q; want the full one", uuid, got)
+				}
+			}
+		})
+	}
+
+	s := openStore(t)
+	var ids []int64
+	for i, description := range []string{"Scheme X", "Scheme X, amended"} {
+		o := opportunity(fmt.Sprintf("other-%d", i), "Other", 1, "r1")
+		o.Classifications = []types.ClassificationCode{
+			{
+				Code:           "123",
+				Classification: description,
+			},
+		}
+		mustSave(t, s, o)
+		ids = append(ids, o.Classifications[0].ID)
+	}
+	if ids[0] == ids[1] {
+		t.Errorf("a non-CPV code's descriptions share a row: %v", ids)
+	}
+}
+
 func TestClassificationRowsAreShared(t *testing.T) {
 	s := openStore(t)
 	a := opportunity("ocds-a", "A", 1, "r1")