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view.sx: persist/view bundles stream + fold + snapshot name; view-attach subscribes it to a hub so each publish refreshes the snapshot incrementally, making view-peek an O(1) current read. view-value always folds the tail so it is never stale. The consumer read-model abstraction (feed indices, audit rollups, search counters). 122/122. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
106 lines
2.9 KiB
Plaintext
106 lines
2.9 KiB
Plaintext
; Extension — materialized views: stay current on write, read O(1) via peek.
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(define vw-count (fn (acc e) (+ acc 1)))
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(define vw (persist/view "order-count" "orders" vw-count 0))
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(persist-test "view-name" (persist/view-name vw) "order-count")
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(persist-test "view-stream" (persist/view-stream vw) "orders")
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(persist-test
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"view-value folds the stream"
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(let
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((b (persist/open)))
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(begin
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(persist/append b "orders" "x" 0 {})
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(persist/append b "orders" "x" 0 {})
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(persist/view-value b vw)))
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2)
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(persist-test
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"view-refresh persists a snapshot that peek then reads"
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(let
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((b (persist/open)))
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(begin
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(persist/append b "orders" "x" 0 {})
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(persist/view-refresh b vw)
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(persist/view-peek b vw)))
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1)
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(persist-test
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"peek lags an un-refreshed tail"
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(let
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((b (persist/open)))
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(begin
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(persist/append b "orders" "x" 0 {})
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(persist/view-refresh b vw)
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(persist/append b "orders" "x" 0 {})
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(persist/view-peek b vw)))
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1)
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(persist-test
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"view-value sees the whole stream even after a stale snapshot"
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(let
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((b (persist/open)))
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(begin
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(persist/append b "orders" "x" 0 {})
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(persist/view-refresh b vw)
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(persist/append b "orders" "x" 0 {})
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(persist/view-value b vw)))
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2)
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(persist-test
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"attached view stays current on publish — peek needs no manual refresh"
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(let
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((b (persist/open)))
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(let
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((h (persist/view-attach (persist/hub b) vw)))
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(begin
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(persist/publish h "orders" "x" 0 {})
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(persist/publish h "orders" "x" 0 {})
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(persist/publish h "orders" "x" 0 {})
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(persist/view-peek b vw))))
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3)
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(persist-test
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"attached view advances the snapshot seq incrementally"
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(let
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((b (persist/open)))
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(let
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((h (persist/view-attach (persist/hub b) vw)))
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(begin
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(persist/publish h "orders" "x" 0 {})
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(persist/publish h "orders" "x" 0 {})
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(persist/project-seq
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(persist/snapshot-load b "order-count" 0)))))
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2)
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(persist-test
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"attach only reacts to its own stream"
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(let
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((b (persist/open)))
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(let
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((h (persist/view-attach (persist/hub b) vw)))
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(begin
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(persist/publish h "other" "x" 0 {})
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(persist/view-peek b vw))))
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0)
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(persist-test
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"materialized view works on the durable backend"
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(let
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((db (persist/mock-durable (persist/mem-backend))))
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(let
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((h (persist/view-attach (persist/hub db) vw)))
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(begin
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(persist/publish h "orders" "x" 0 {})
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(persist/publish h "orders" "x" 0 {})
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(persist/view-peek db vw))))
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2)
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(persist-test
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"view sum over event data"
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(let
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((b (persist/open))
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(sumv
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(persist/view
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"rev"
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"sales"
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(fn (acc e) (+ acc (get (persist/event-data e) :amt)))
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0)))
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(begin
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(persist/append b "sales" "sale" 0 {:amt 10})
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(persist/append b "sales" "sale" 1 {:amt 25})
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(persist/view-value b sumv)))
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35)
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