After OAuth flows (8 Oct), this post covers optimistic concurrency: version columns, If-Match/ETag, 409 conflicts, OCC vs locks, document revs, batch items, merge UX and metrics.

आशावादीबन्धः: A Metrical Codification of Optimistic Concurrency (with English glosses)

What this post is about

Optimistic concurrency control (OCC) detects lost updates with versions/ETags instead of long-held locks.

Topics covered

1. Lost updates
2. Version column + conditional UPDATE
3. HTTP ETag / If-Match
4. 409 Conflict responses
5. OCC vs pessimistic locks
6. Document revisions / CAS
7. Batch item versions
8. Client merge UX
9. Conflict-rate metrics
10. OCC vs idempotency keys

Sanskrit title

आशावादीबन्धः = āśāvādī-bandhaḥ “optimistic binding/lock”.

English

Minimizable; Sanskrit-first.

ग्राह्यम् / Keep

१. versionस्तम्भः: monotonic per row
२. conditional write: WHERE version / If-Match
३. 409स्पश: conflict with reload hint
४. ETag expose: on readable resources
५. merge UX: show both sides
६. conflict metrics: tune hot resources
७. short OCC: small documents prefer OCC

त्याज्यम् / Avoid

• last-write-wins on balances
• PUT without If-Match on shared docs
• ignore 0-row updates as success

पदच्छेदः
द्वौ यदि एकं लेखं सह लिखतः तदा अन्तिमः मा अन्धः । आशावादीबन्धस्तस्माद् संस्करणसत्यम् ॥१॥

Word-for-word

Gloss table

English sense
Optimistic concurrency control detects lost updates using a version column or ETag instead of holding long DB locks.

Context / topic
Topic: lost update problem.

वृत्तमिति: ८-८-८-८।

पदच्छेदः
version स्तम्भः प्रत्येकं सिद्धलेखे वर्धताम् । WHERE version=old अनिवार्यम् ॥२॥

Word-for-word

Gloss table

English sense
Updates must include the version the client read. If zero rows match, someone else won: return 409 Conflict.

Context / topic
Topic: version column pattern.

वृत्तमिति: ८-८-८-८।

पदच्छेदः
ETag If-Match HTTP पक्षे । body alone आशा मुषा ॥३॥

Word-for-word

Gloss table

English sense
REST APIs can expose ETag and require If-Match on PUT/PATCH so intermediaries and clients speak the same concurrency language.

Context / topic
Topic: HTTP conditional requests.

वृत्तमिति: ८-८-८-८।

पदच्छेदः
conflict उत्तरं स्पशं 409 । मौनoverwrite विश्वासं हन्ति ॥४॥

Word-for-word

Gloss table

English sense
On version mismatch tell the client to reload and merge. Silent last-write-wins is rarely acceptable for money or clinical data.

Context / topic
Topic: conflict UX/API.

वृत्तमिति: ८-८-८-८।

पदच्छेदः
pessimistic तालः दीर्घे खण्डे optimistic बहुपठने । उभौ शस्त्रे युद्धं भिन्दु ॥५॥

Word-for-word

Gloss table

English sense
Use pessimistic locks for short hot critical sections with high conflict; optimistic for read-heavy resources with rare writes.

Context / topic
Topic: optimistic vs pessimistic. Links to distributed lock.

वृत्तमिति: एकादशाक्षराः पादाः।

पदच्छेदः
document store rev/_etag समानधर्मः । CAS तुलना-swap ॥६॥

Word-for-word

Gloss table

English sense
Couch/Mongo/etc. revisions are the same idea: compare-and-swap on the revision you read.

Context / topic
Topic: document revisions.

वृत्तमिति: ८-८-८-८।

पदच्छेदः
बैचलेखे प्रत्येकं संस्करणं वहेत् । एकfail सर्वं वा नीतिः ॥७॥

Word-for-word

Gloss table

English sense
Batch updates need per-item versions and stated atomicity: abort all or report partial conflicts.

Context / topic
Topic: batch + versions. Links to batch API.

वृत्तमिति: ८-८-८-८।

पदच्छेदः
UI merge tools conflict दर्शयेत् । अन्धपुनर्लेखः द्वेषाय ॥८॥

Word-for-word

Gloss table

English sense
Clients should show concurrent edits and help merge rather than looping PUT until it sticks.

Context / topic
Topic: client merge UX.

वृत्तमिति: ८-८-८-८।

पदच्छेदः
मापनं 409 दरः useful । अतिसंघर्षे redesign ॥९॥

Word-for-word

Gloss table

English sense
High conflict rates mean the resource is too hot: shard, queue writes or switch to explicit locking.

Context / topic
Topic: metrics-driven redesign.

वृत्तमिति: ८-८-८-८।

पदच्छेदः
इदमर्थकुञ्चिका जन्म रक्षति version संघर्षे रक्षति । उभौ भिन्ने उभौ रक्षके ॥१०॥

Word-for-word

Gloss table

English sense
Idempotency keys dedupe the same intent; versions protect concurrent different intents on one row. You often need both.

Context / topic
Topic: idempotency vs OCC.

सन्धिः: कुञ्चिका द्विः मा; version सह मा नश्यतु।

वृत्तमिति: एकादशाक्षराः पादाः।

पदच्छेदः
version स्तम्भः If-Match 409 merge मापनं पञ्चकम् । एभिराशावादीबन्धः लेखसत्यसमन्वितः ॥११॥

Word-for-word

Gloss table

English sense
Five limbs: version/ETag, conditional write, clear 409, client merge path and conflict metrics.

Context / topic
Topic: checklist.

वृत्तमिति: ८-८-८-८।

पदच्छेदः
इत्याशावादीबन्धसारो लेखसत्यसमन्वितः । मितं संघर्षं क्रियायोग्यं तन्त्रधर्मः स उच्यते ॥१२॥

Word-for-word

Gloss table

English sense
Closing: hope the quiet path but always detect when two writers met.

Context / topic
Topic: close.

उपसंहारन्यायः: पठितversionं वह; सिद्धे वर्धय; संघर्षे सत्यं वद।

वृत्तमिति: ८-८-८-८।

१. Lost update
२. Version column
३. HTTP ETag
४. 409
५. OCC vs lock
६. Document CAS
७. Batch
८. Merge UX
९. Metrics
१०. Idempotency contrast
११. Five limbs
१२. Close

1. Prior: distributed lock 2026-09-29; idempotency 2026-10-04; batch 2026-10-03; migrations 2026-09-06.
2. Domain: OCC version/ETag patterns.
3. English minimizable; Sanskrit-first.
4. Style: no em dash; no Oxford comma in English clauses.