diff --git a/kustomize/base/candles-cache-worker/worker.mjs b/kustomize/base/candles-cache-worker/worker.mjs
index 7c152af..39ba680 100644
--- a/kustomize/base/candles-cache-worker/worker.mjs
+++ b/kustomize/base/candles-cache-worker/worker.mjs
@@ -144,7 +144,14 @@ function chunkSecondsForBucket(bucketSeconds) {
 
 function sqlUpsertCandlesFromTicks({ symbol, sourceKey, bucketSeconds, fromIso, toIso }) {
   return `
-    WITH base AS (
+    WITH chosen AS (
+      SELECT source AS chosen_source
+      FROM public.drift_ticks
+      WHERE symbol = ${sqlLit(symbol)}
+      ORDER BY ts DESC
+      LIMIT 1
+    ),
+    base AS (
       SELECT
         time_bucket(make_interval(secs => ${bucketSeconds}), ts) AS bucket,
         ts,
@@ -154,7 +161,10 @@ function sqlUpsertCandlesFromTicks({ symbol, sourceKey, bucketSeconds, fromIso,
       WHERE symbol = ${sqlLit(symbol)}
         AND ts >= ${sqlLit(fromIso)}::timestamptz
         AND ts < ${sqlLit(toIso)}::timestamptz
-        AND (${sqlLit(sourceKey)} = '' OR source = ${sqlLit(sourceKey)})
+        AND (
+          ${sqlLit(sourceKey)} <> '' AND source = ${sqlLit(sourceKey)}
+          OR ${sqlLit(sourceKey)} = '' AND source = COALESCE((SELECT chosen_source FROM chosen), source)
+        )
     ),
     agg AS (
       SELECT
@@ -195,11 +205,26 @@ function sqlDeleteOlderCandles({ symbol, sourceKey, bucketSeconds, cutoffIso })
 }
 
 async function getTickRange(cfg, { symbol, sourceKey }) {
-  const sql = `
+  const sql =
+    String(sourceKey) === ''
+      ? `
+    WITH chosen AS (
+      SELECT source AS chosen_source
+      FROM public.drift_ticks
+      WHERE symbol=${sqlLit(symbol)}
+      ORDER BY ts DESC
+      LIMIT 1
+    )
     SELECT min(ts) AS min_ts, max(ts) AS max_ts
     FROM public.drift_ticks
     WHERE symbol=${sqlLit(symbol)}
-      AND (${sqlLit(sourceKey)} = '' OR source = ${sqlLit(sourceKey)});
+      AND source = COALESCE((SELECT chosen_source FROM chosen), source);
+  `
+      : `
+    SELECT min(ts) AS min_ts, max(ts) AS max_ts
+    FROM public.drift_ticks
+    WHERE symbol=${sqlLit(symbol)}
+      AND source = ${sqlLit(sourceKey)};
   `;
   const out = await hasuraRunSql(cfg, sql, { readOnly: true });
   const row = Array.isArray(out?.result) && out.result.length >= 2 ? out.result[1] : null;
diff --git a/kustomize/base/initdb/001_init.sql b/kustomize/base/initdb/001_init.sql
index 7f601b1..349e8bc 100644
--- a/kustomize/base/initdb/001_init.sql
+++ b/kustomize/base/initdb/001_init.sql
@@ -162,27 +162,52 @@ RETURNS SETOF public.drift_candles
 LANGUAGE sql
 STABLE
 AS $$
-  WITH base AS (
+  WITH src AS (
+    SELECT COALESCE(p_source, '') AS source_key
+  ),
+  cached AS (
+    SELECT
+      c.bucket,
+      c.open,
+      c.high,
+      c.low,
+      c.close,
+      c.oracle_close,
+      c.ticks
+    FROM public.drift_candles_cache c, src
+    WHERE c.symbol = p_symbol
+      AND c.bucket_seconds = p_bucket_seconds
+      AND c.source = src.source_key
+    ORDER BY c.bucket DESC
+    LIMIT p_limit
+  ),
+  fallback AS (
     SELECT
       time_bucket(make_interval(secs => p_bucket_seconds), ts) AS bucket,
       ts,
       COALESCE(mark_price, oracle_price) AS px,
       oracle_price AS oracle_px
-    FROM public.drift_ticks
+    FROM public.drift_ticks, src
     WHERE symbol = p_symbol
-      AND (p_source IS NULL OR source = p_source)
+      AND (src.source_key = '' OR source = src.source_key)
       AND ts >= now() - make_interval(secs => (p_bucket_seconds * p_limit * 2))
+  ),
+  computed AS (
+    SELECT
+      bucket,
+      (array_agg(px ORDER BY ts ASC))[1] AS open,
+      max(px) AS high,
+      min(px) AS low,
+      (array_agg(px ORDER BY ts DESC))[1] AS close,
+      (array_agg(oracle_px ORDER BY ts DESC))[1] AS oracle_close,
+      count(*) AS ticks
+    FROM fallback
+    GROUP BY bucket
   )
-  SELECT
-    bucket,
-    (array_agg(px ORDER BY ts ASC))[1] AS open,
-    max(px) AS high,
-    min(px) AS low,
-    (array_agg(px ORDER BY ts DESC))[1] AS close,
-    (array_agg(oracle_px ORDER BY ts DESC))[1] AS oracle_close,
-    count(*) AS ticks
-  FROM base
-  GROUP BY bucket
+  SELECT * FROM cached
+  UNION ALL
+  SELECT * FROM computed
+  WHERE NOT EXISTS (SELECT 1 FROM cached)
   ORDER BY bucket DESC
   LIMIT p_limit;
 $$;