After API versioning (27 Sep), this post covers the transactional outbox: atomic business+event birth, relay publishers, states, lag, purge and consumer inbox dedupe.

बहिर्लेखनपटलः: A Metrical Codification of the Transactional Outbox (with English glosses)

What this post is about

The transactional outbox avoids dual-write bugs by storing outbound events in the same DB transaction as the business update then publishing them with a relay.

Topics covered

1. Dual-write failure mode
2. Same-transaction outbox rows
3. Relay publisher
4. pending/sent/failed states
5. Ordering via keys
6. Poison rows
7. Lag metrics
8. Purge retention
9. Consumer inbox idempotency
10. Link to message queues

Sanskrit title

बहिर्लेखनपटलः = bahir-lekhana-paṭalaḥ “tablet/surface for outward writing” (outbox).

ग्राह्यम् / Keep

१. एकव्यवहारः: business+outbox one txn
२. प्रकाशकरिले: ack then mark sent
३. स्थितिमापनम्: lag age depth
४. विषनिरोधः: poison quarantine
५. शुद्धिः: sent-row retention
६. इनबॉक्स: consumer dedupe
७. घटनाID: stable event identity

त्याज्यम् / Avoid

• DB commit then best-effort publish only
• infinite retry poison
• never measure outbox lag

पदच्छेदः
द्विलेखने यदि एकं सिध्येद् अन्यत् नश्येत् तदा असत्यम् । बहिर्लेखनपटलस्तस्माद् एकसत्यसेतुः ॥१॥

Word-for-word

Gloss table

English sense
Writing the database and then separately publishing to a queue can leave one side done and the other not. The outbox pattern writes the business row and an outbox row in one transaction then publishes asynchronously.

Context / topic
Topic: dual-write problem and outbox fix.

वृत्तमिति: ८-८-८-८।

पदच्छेदः
व्यवहारलेखः पटललेखश्च एकस्मिन् व्यवहारे । ततः एव परमाणुसत्यम् ॥२॥

Word-for-word

Gloss table

English sense
Both rows commit together or neither does. That atomicity is the whole point.

Context / topic
Topic: same-transaction outbox insert.

वृत्तमिति: ८-८-८-८।

पदच्छेदः
प्रकाशकः पटलं पठित्वा पङ्क्तौ क्षिपेत् । क्रमेण इदमर्थया च ॥३॥

Word-for-word

Gloss table

English sense
A relay polls or tails the outbox and publishes. Marks sent only after broker ack. Uses idempotent event ids for at-least-once buses.

Context / topic
Topic: relay publisher.

वृत्तमिति: ८-८-८-८।

पदच्छेदः
स्थितिः pending sent failed लेख्या पटले । अदृश्यस्थितौ पुनर्यत्नो अन्धः ॥४॥

Word-for-word

Gloss table

English sense
Track delivery state on each outbox row for ops and replay.

Context / topic
Topic: outbox row state machine.

वृत्तमिति: ८-८-८-८।

पदच्छेदः
क्रमः विभाजकेन रक्ष्यः यदि व्यवसाये क्रमः इष्टः । विश्वपङ्क्तौ क्रमः न जादू ॥५॥

Word-for-word

Gloss table

English sense
If order matters use keys that hash to one partition and document the guarantee. Do not assume total global order.

Context / topic
Topic: ordering guarantees.

वृत्तमिति: एकादशाक्षराः पादाः।

पदच्छेदः
मृतपङ्क्तिसदृशं failed पटलम् आलोक्यम् । विषघटना मा अनन्तयत्नम् ॥६॥

Word-for-word

Gloss table

English sense
Poison payloads need quarantine metrics and human paths not infinite relays.

Context / topic
Topic: poison outbox rows. Links to queue DLQ.

वृत्तमिति: ८-८-८-८।

पदच्छेदः
पटलवृद्धिः माप्या पङ्क्तिगांभीर्यवत् । अदृश्यब्याकलॉग् विपत्तिः ॥७॥

Word-for-word

Gloss table

English sense
Alert on outbox lag age and depth. A stuck relay is a silent integration outage.

Context / topic
Topic: outbox lag SLOs.

वृत्तमिति: ८-८-८-८।

पदच्छेदः
शुद्धिः sent पङ्क्तीनां धारणेन मिता । अनन्तपटलं भण्डारं दह्यते ॥८॥

Word-for-word

Gloss table

English sense
Purge successfully sent rows on a retention clock. The outbox is not forever history unless you designed it so.

Context / topic
Topic: retention. Links to data lifecycle.

वृत्तमिति: ८-८-८-८।

पदच्छेदः
इनबॉक्स प्रतिपक्षे द्विः उपभोगं वारयेत् । पटलं ददाति इनबॉक्स रक्षति ॥९॥

Word-for-word

Gloss table

English sense
Producers use outbox; consumers often need inbox idempotency keys so at-least-once delivery does not double-apply.

Context / topic
Topic: inbox counterpart.

वृत्तमिति: ८-८-८-८।

पदच्छेदः
सन्देशपङ्क्तिशास्त्रं वहनं वदति पटलं जन्म सत्यं वदति । उभौ विना घटना मिथ्या ॥१०॥

Word-for-word

Gloss table

English sense
Queues move messages; the outbox decides they were born with the business commit. You usually need both ideas.

Context / topic
Topic: link to message queues (29 Jul).

सन्धिः: पङ्क्तिः पथः; पटलः जन्म।

वृत्तमिति: एकादशाक्षराः पादाः।

पदच्छेदः
एकव्यवहारः प्रकाशकः स्थितिः शुद्धिः इनबॉक्स पञ्चकम् । एभिर्बहिर्लेखनपटलं एकसत्यसमन्वितम् ॥११॥

Word-for-word

Gloss table

English sense
Five limbs: atomic outbox write, relay publisher, visible states, retention purge and consumer inbox dedupe.

Context / topic
Topic: checklist.

वृत्तमिति: ८-८-८-८।

पदच्छेदः
इति बहिर्लेखनपटलसार एकसत्यसमन्वितः । मितं प्रकाशनं क्रियायोग्यं तन्त्रधर्मः स उच्यते ॥१२॥

Word-for-word

Gloss table

English sense
Closing: never split the business fact from the event birth without a transactional bridge.

Context / topic
Topic: close.

उपसंहारन्यायः: एकस्मिन् व्यवहारे जन्म; ततः प्रकाशः।

वृत्तमिति: ८-८-८-८।

१. Dual-write problem
२. Atomic insert
३. Relay
४. States
५. Ordering
६. Poison
७. Lag metrics
८. Purge
९. Inbox
१०. Queue link
११. Five limbs
१२. Close

1. Prior: queues 2026-07-29; workflow 2026-07-28; retry 2026-08-14.
2. Domain: transactional outbox and inbox idempotency.
3. Bilingual word-for-word + sense.
4. Style: no em dash; no Oxford comma in English clauses.