We are considering a PostgreSQL jobs table consumed by three workers. Use https://www.postgresql.org/docs/current/sql-select.html to compare FOR UPDATE SKIP LOCKED with a normal SELECT for claiming jobs. Produce a decision table plus a transaction outline. Explain the inconsistent-view caveat, why queue-like use differs from general-purpose reads, and which crash/idempotency questions the SELECT documentation does not resolve.
10/4/2026, 11:39:07 PM · llm:deepseek:deepseek-v4-flash
> ⚠ Low confidence — Only source excerpts are delivered; complete synthesis and per-assertion support remain unverified. Evidence assessment: 3 sub-claims remain below the evidence threshold within budget. Treat this as provisional.
Source excerpts only. The draft is withheld as a conclusion; complete synthesis is unverified. Qualifying source excerpts are quoted below. Research targets are topics to investigate, not established conclusions.
Research target 1
Requested topic (unverified): “According to https://www.postgresql.org/docs/current/sql-select.html, how does FOR UPDATE SKIP LOCKED behave when claiming jobs from a PostgreSQL jobs table consumed by three workers?”
- “SKIP LOCKED (PostgreSQL 9.5 and later) is for "give me something else": it treats locked rows as if they did not exist for this statement.” - “FOR UPDATE SKIP LOCKED turns an ordinary PostgreSQL table into a safe, concurrent job queue.” - “Select ready work by schedule and priority with FOR UPDATE SKIP LOCKED, assign lease owner and expiry, then commit.”
Research target 2
Requested topic (unverified): “According to https://www.postgresql.org/docs/current/sql-select.html, how does a normal SELECT behave when claiming jobs from a PostgreSQL jobs table consumed by three workers?”
Evidence gap: no qualifying excerpt for this research target.
Research target 3
Requested topic (unverified): “According to https://www.postgresql.org/docs/current/sql-select.html, what is the inconsistent-view caveat for SELECT, and how does it apply to FOR UPDATE SKIP LOCKED versus a normal SELECT?”
- “The documentation is explicit that this yields an inconsistent view of the data, and that is intentional; for a queue, an inconsistent view is exactly what you want, because each worker should see a different subset of available rows.” - “PostgreSQL documents that SKIP LOCKED provides an inconsistent view unsuitable for general queries but useful for multiple consumers accessing a queue-like table.”
Research target 4
Requested topic (unverified): “According to https://www.postgresql.org/docs/current/sql-select.html, why does queue-like use of SELECT differ from general-purpose reads?”
- “PostgreSQL documents that SKIP LOCKED provides an inconsistent view unsuitable for general queries but useful for multiple consumers accessing a queue-like table.” - “The documentation is explicit that this yields an inconsistent view of the data, and that is intentional; for a queue, an inconsistent view is exactly what you want, because each worker should see a different subset of available rows.”
Research target 5
Requested topic (unverified): “According to https://www.postgresql.org/docs/current/sql-select.html, which crash questions about claiming jobs are not resolved by the SELECT documentation?”
- “A worker can crash after claiming, repeat a side effect after losing a response, starve old jobs behind priority traffic, hold a transaction too long, or retry poison work forever.” - “The queue needs leases, idempotent handlers, retry policy, terminal states, indexes, and observable recovery.”
Evidence gap: the recorded assessment remains below the support threshold for this target.
Research target 6
Requested topic (unverified): “According to https://www.postgresql.org/docs/current/sql-select.html, which idempotency questions about claiming jobs are not resolved by the SELECT documentation?”
- “The queue needs leases, idempotent handlers, retry policy, terminal states, indexes, and observable recovery.” - “A worker can crash after claiming, repeat a side effect after losing a response, starve old jobs behind priority traffic, hold a transaction too long, or retry poison work forever.”
Evidence gap: the recorded assessment remains below the support threshold for this target.
Excerpts establish source grounding, not factual truth, entailment or whole-paper coverage. Support and coverage are estimates, not certification of a complete answer. Source statements may be wrong or conflicting. Draft conclusions are withheld; inspect the original text and obtain further review. Payment states remain in the separate receipt.
Next steps to complete this research
These are suggested follow-up steps; this run has not performed them. They do not change the recorded evidence or payment state.
- “Building a PostgreSQL Job Queue with FOR UPDATE SKIP LOCKED Akshay Gupta”: HTML text extraction failed. Look for a publisher-provided text/PDF edition of the same document and version; a preview cannot replace the original content.
- “SELECT ... FOR UPDATE SKIP LOCKED: The Right Way to Build a Concurrent Job Queue in PostgreSQL QueryStack”: HTML text extraction failed. Look for a publisher-provided text/PDF edition of the same document and version; a preview cannot replace the original content.
Evidence ledger — recorded source excerpts
Research targets are unverified topics. Coverage is an estimate of excerpt support, not proof of entailment, factual truth or a complete answer.
Requested topic (unverified): “According to https://www.postgresql.org/docs/current/sql-select.html, how does FOR UPDATE SKIP LOCKED behave when claiming jobs from a PostgreSQL jobs table consumed by three workers?”
40% estimated“SKIP LOCKED (PostgreSQL 9.5 and later) is for "give me something else": it treats locked rows as if they did not exist for this statement.” [S2] Postgres SELECT FOR UPDATE SKIP LOCKED: Job Queues – Chat2DB
“FOR UPDATE SKIP LOCKED turns an ordinary PostgreSQL table into a safe, concurrent job queue.” [S2] Postgres SELECT FOR UPDATE SKIP LOCKED: Job Queues – Chat2DB
“Select ready work by schedule and priority with FOR UPDATE SKIP LOCKED, assign lease owner and expiry, then commit.” [S1] Build a PostgreSQL worker queue with SKIP LOCKED
Requested topic (unverified): “According to https://www.postgresql.org/docs/current/sql-select.html, how does a normal SELECT behave when claiming jobs from a PostgreSQL jobs table consumed by three workers?”
0% estimatedNo qualifying excerpt recorded
Requested topic (unverified): “According to https://www.postgresql.org/docs/current/sql-select.html, what is the inconsistent-view caveat for SELECT, and how does it apply to FOR UPDATE SKIP LOCKED versus a normal SELECT?”
40% estimated“The documentation is explicit that this yields an inconsistent view of the data, and that is intentional; for a queue, an inconsistent view is exactly what you want, because each worker should see a different subset of available rows.” [S2] Postgres SELECT FOR UPDATE SKIP LOCKED: Job Queues – Chat2DB
“PostgreSQL documents that SKIP LOCKED provides an inconsistent view unsuitable for general queries but useful for multiple consumers accessing a queue-like table.” [S1] Build a PostgreSQL worker queue with SKIP LOCKED
Requested topic (unverified): “According to https://www.postgresql.org/docs/current/sql-select.html, why does queue-like use of SELECT differ from general-purpose reads?”
40% estimated“PostgreSQL documents that SKIP LOCKED provides an inconsistent view unsuitable for general queries but useful for multiple consumers accessing a queue-like table.” [S1] Build a PostgreSQL worker queue with SKIP LOCKED
“The documentation is explicit that this yields an inconsistent view of the data, and that is intentional; for a queue, an inconsistent view is exactly what you want, because each worker should see a different subset of available rows.” [S2] Postgres SELECT FOR UPDATE SKIP LOCKED: Job Queues – Chat2DB
Requested topic (unverified): “According to https://www.postgresql.org/docs/current/sql-select.html, which crash questions about claiming jobs are not resolved by the SELECT documentation?”
20% estimated“A worker can crash after claiming, repeat a side effect after losing a response, starve old jobs behind priority traffic, hold a transaction too long, or retry poison work forever.” [S1] Build a PostgreSQL worker queue with SKIP LOCKED
“The queue needs leases, idempotent handlers, retry policy, terminal states, indexes, and observable recovery.” [S1] Build a PostgreSQL worker queue with SKIP LOCKED
Requested topic (unverified): “According to https://www.postgresql.org/docs/current/sql-select.html, which idempotency questions about claiming jobs are not resolved by the SELECT documentation?”
20% estimated“The queue needs leases, idempotent handlers, retry policy, terminal states, indexes, and observable recovery.” [S1] Build a PostgreSQL worker queue with SKIP LOCKED
“A worker can crash after claiming, repeat a side effect after losing a response, starve old jobs behind priority traffic, hold a transaction too long, or retry poison work forever.” [S1] Build a PostgreSQL worker queue with SKIP LOCKED
What if a source were missing?
Temporarily leave out one source to see which research targets retain excerpts in this report.
Showing the original excerpt ledger. 1 target already had no inspectable excerpts.
According to https://www.postgresql.org/docs/current/sql-select.html, how does FOR UPDATE SKIP LOCKED behave when claiming jobs from a PostgreSQL jobs table consumed by three workers?
3 recorded excerpts remain.
Inspect remaining excerpts
“SKIP LOCKED (PostgreSQL 9.5 and later) is for "give me something else": it treats locked rows as if they did not exist for this statement.”
S2 · chat2db.ai · Postgres SELECT FOR UPDATE SKIP LOCKED: Job Queues – Chat2DB · version 70c229f1aa1d0d45e231bb443b88fb8971f3a1d0a0c7c3ca7ea4acc6df790fb5
“FOR UPDATE SKIP LOCKED turns an ordinary PostgreSQL table into a safe, concurrent job queue.”
S2 · chat2db.ai · Postgres SELECT FOR UPDATE SKIP LOCKED: Job Queues – Chat2DB · version 70c229f1aa1d0d45e231bb443b88fb8971f3a1d0a0c7c3ca7ea4acc6df790fb5
“Select ready work by schedule and priority with FOR UPDATE SKIP LOCKED, assign lease owner and expiry, then commit.”
S1 · jpcasabianca.com · Build a PostgreSQL worker queue with SKIP LOCKED · version 895e4919add44f70ab5f4f9faf5a279818795815f02a5a4ed16ac5c937c877da
According to https://www.postgresql.org/docs/current/sql-select.html, how does a normal SELECT behave when claiming jobs from a PostgreSQL jobs table consumed by three workers?
No inspectable excerpts in the original report.
According to https://www.postgresql.org/docs/current/sql-select.html, what is the inconsistent-view caveat for SELECT, and how does it apply to FOR UPDATE SKIP LOCKED versus a normal SELECT?
2 recorded excerpts remain.
Inspect remaining excerpts
“The documentation is explicit that this yields an inconsistent view of the data, and that is intentional; for a queue, an inconsistent view is exactly what you want, because each worker should see a different subset of available rows.”
S2 · chat2db.ai · Postgres SELECT FOR UPDATE SKIP LOCKED: Job Queues – Chat2DB · version 70c229f1aa1d0d45e231bb443b88fb8971f3a1d0a0c7c3ca7ea4acc6df790fb5
“PostgreSQL documents that SKIP LOCKED provides an inconsistent view unsuitable for general queries but useful for multiple consumers accessing a queue-like table.”
S1 · jpcasabianca.com · Build a PostgreSQL worker queue with SKIP LOCKED · version 895e4919add44f70ab5f4f9faf5a279818795815f02a5a4ed16ac5c937c877da
According to https://www.postgresql.org/docs/current/sql-select.html, why does queue-like use of SELECT differ from general-purpose reads?
2 recorded excerpts remain.
Inspect remaining excerpts
“PostgreSQL documents that SKIP LOCKED provides an inconsistent view unsuitable for general queries but useful for multiple consumers accessing a queue-like table.”
S1 · jpcasabianca.com · Build a PostgreSQL worker queue with SKIP LOCKED · version 895e4919add44f70ab5f4f9faf5a279818795815f02a5a4ed16ac5c937c877da
“The documentation is explicit that this yields an inconsistent view of the data, and that is intentional; for a queue, an inconsistent view is exactly what you want, because each worker should see a different subset of available rows.”
S2 · chat2db.ai · Postgres SELECT FOR UPDATE SKIP LOCKED: Job Queues – Chat2DB · version 70c229f1aa1d0d45e231bb443b88fb8971f3a1d0a0c7c3ca7ea4acc6df790fb5
According to https://www.postgresql.org/docs/current/sql-select.html, which crash questions about claiming jobs are not resolved by the SELECT documentation?
2 recorded excerpts remain.
Inspect remaining excerpts
“A worker can crash after claiming, repeat a side effect after losing a response, starve old jobs behind priority traffic, hold a transaction too long, or retry poison work forever.”
S1 · jpcasabianca.com · Build a PostgreSQL worker queue with SKIP LOCKED · version 895e4919add44f70ab5f4f9faf5a279818795815f02a5a4ed16ac5c937c877da
“The queue needs leases, idempotent handlers, retry policy, terminal states, indexes, and observable recovery.”
S1 · jpcasabianca.com · Build a PostgreSQL worker queue with SKIP LOCKED · version 895e4919add44f70ab5f4f9faf5a279818795815f02a5a4ed16ac5c937c877da
According to https://www.postgresql.org/docs/current/sql-select.html, which idempotency questions about claiming jobs are not resolved by the SELECT documentation?
2 recorded excerpts remain.
Inspect remaining excerpts
“The queue needs leases, idempotent handlers, retry policy, terminal states, indexes, and observable recovery.”
S1 · jpcasabianca.com · Build a PostgreSQL worker queue with SKIP LOCKED · version 895e4919add44f70ab5f4f9faf5a279818795815f02a5a4ed16ac5c937c877da
“A worker can crash after claiming, repeat a side effect after losing a response, starve old jobs behind priority traffic, hold a transaction too long, or retry poison work forever.”
S1 · jpcasabianca.com · Build a PostgreSQL worker queue with SKIP LOCKED · version 895e4919add44f70ab5f4f9faf5a279818795815f02a5a4ed16ac5c937c877da
Targets are requested topics, not verified assertions. Excerpts do not prove truth or independent corroboration. This view keeps the answer, confidence and payments unchanged and makes no new requests.
Research evidence matrix
Compare unverified research targets with cited sources and inspect recorded excerpts. An empty cell means no inspectable excerpt was recorded; it does not establish whether a claim is true, false, or disputed. Coverage and agent confidence do not prove entailment, measured accuracy or complete synthesis.
| Research target (unverified) | Inspection status | [S1] Build a PostgreSQL worker queue with SKIP LOCKEDPublication: jpcasabianca.comPublished: Not recorded | [S2] Postgres SELECT FOR UPDATE SKIP LOCKED: Job Queues – Chat2DBPublication: chat2db.aiPublished: Not recorded |
|---|---|---|---|
| According to https://www.postgresql.org/docs/current/sql-select.html, how does FOR UPDATE SKIP LOCKED behave when claiming jobs from a PostgreSQL jobs table consumed by three workers? | Recorded excerpt | Inspect 1 excerptSelect ready work by schedule and priority with FOR UPDATE SKIP LOCKED, assign lease owner and expiry, then commit. | Inspect 2 excerptsSKIP LOCKED (PostgreSQL 9.5 and later) is for "give me something else": it treats locked rows as if they did not exist for this statement. FOR UPDATE SKIP LOCKED turns an ordinary PostgreSQL table into a safe, concurrent job queue. |
| According to https://www.postgresql.org/docs/current/sql-select.html, how does a normal SELECT behave when claiming jobs from a PostgreSQL jobs table consumed by three workers? | No inspectable excerpt recorded | No excerpt recorded | No excerpt recorded |
| According to https://www.postgresql.org/docs/current/sql-select.html, what is the inconsistent-view caveat for SELECT, and how does it apply to FOR UPDATE SKIP LOCKED versus a normal SELECT? | Recorded excerpt | Inspect 1 excerptPostgreSQL documents that SKIP LOCKED provides an inconsistent view unsuitable for general queries but useful for multiple consumers accessing a queue-like table. | Inspect 1 excerptThe documentation is explicit that this yields an inconsistent view of the data, and that is intentional; for a queue, an inconsistent view is exactly what you want, because each worker should see a different subset of available rows. |
| According to https://www.postgresql.org/docs/current/sql-select.html, why does queue-like use of SELECT differ from general-purpose reads? | Recorded excerpt | Inspect 1 excerptPostgreSQL documents that SKIP LOCKED provides an inconsistent view unsuitable for general queries but useful for multiple consumers accessing a queue-like table. | Inspect 1 excerptThe documentation is explicit that this yields an inconsistent view of the data, and that is intentional; for a queue, an inconsistent view is exactly what you want, because each worker should see a different subset of available rows. |
| According to https://www.postgresql.org/docs/current/sql-select.html, which crash questions about claiming jobs are not resolved by the SELECT documentation? | Recorded excerpt | Inspect 2 excerptsA worker can crash after claiming, repeat a side effect after losing a response, starve old jobs behind priority traffic, hold a transaction too long, or retry poison work forever. The queue needs leases, idempotent handlers, retry policy, terminal states, indexes, and observable recovery. | No excerpt recorded |
| According to https://www.postgresql.org/docs/current/sql-select.html, which idempotency questions about claiming jobs are not resolved by the SELECT documentation? | Recorded excerpt | Inspect 2 excerptsThe queue needs leases, idempotent handlers, retry policy, terminal states, indexes, and observable recovery. A worker can crash after claiming, repeat a side effect after losing a response, starve old jobs behind priority traffic, hold a transaction too long, or retry poison work forever. | No excerpt recorded |
Reference export
2 article references. Recorded titles, links and dates; observed scholarly records also include supplied authors, DOI and journal metadata with read limits. Review metadata before using in a paper. Import RIS into Zotero with File → Import.
Cited sources and references
- 1Build a PostgreSQL worker queue with SKIP LOCKEDjpcasabianca.comFree public reference · no creator payment · extracted html text45%
- 2Postgres SELECT FOR UPDATE SKIP LOCKED: Job Queues – Chat2DBchat2db.aiFree public reference · no creator payment · extracted html text55%
Decision log · 72 steps
Breaking down: "We are considering a PostgreSQL jobs table consumed by three workers. Use https://www.postgresql.org/docs/current/sql-select.html to compare FOR UPDATE SKIP LOCKED with a normal SELECT for claiming jobs. Produce a decision table plus a transaction outline. Explain the inconsistent-view caveat, why queue-like use differs from general-purpose reads, and which crash/idempotency questions the SELECT documentation does not resolve."
Identified 6 research target(s) to investigate; these are not established facts
Deep mode: up to 4 paid/cached/public reads plus one bounded gap-expansion pass when needed.
Web search: 4/4 planned queries attempted, 4 succeeded, 24 public page previews, 0 unavailable queries. Snippets are discovery only. Public reads spend no USDC; model and service operating costs remain separate.
Discovered 0 verified creator source(s) and 24 free public reference(s)
Claim-aware portfolio (exhaustive; bounded selection, not a claim of global optimality) selected 4/17 positive proposal(s): 4 free/cache selections + 0 paid fresh selections, predicting 6/6 claim(s) above the evidence floor with $0.000000/$0.015000 fetch USDC reserved.
Free-preview pre-check maps an actionable source to every sub-claim (6/6); paid reading may proceed within the budget.
Free public-web read; preview directly covers SKIP LOCKED behavior, the inconsistent-view caveat, queue-like vs general-purpose use, and explicitly promises transaction boundary, crash recovery, retries, and idempotency — matching all six sub-claims including the crash/idempotency gaps. - free public original-page READ selection (not a cache hit); no purchase or creator reward. — selected for the claim-aware evidence portfolio (targets claims 1, 2, 3, 4, 5, 6; 0 fetch USDC, 1 attention slot).
Preview quotes the docs' inconsistent-view/queue-like guidance and discusses short claim transactions, leases for abandoned claims, and per-handler idempotency receipts — supports claims 2,3,4,5. - free public original-page READ selection (not a cache hit); no purchase or creator reward. — selected for the claim-aware evidence portfolio (targets claims 3, 4, 5, 6; 0 fetch USDC, 1 attention slot).
Preview warns that claim and update must be in one transaction, that SKIP LOCKED returns intentionally inconsistent results unsuitable for reporting, and that ORDER BY+LIMIT is not strict FIFO — supports claims 0,1,2,3. - free public original-page READ selection (not a cache hit); no purchase or creator reward. — selected for the claim-aware evidence portfolio (targets claims 1, 2, 3, 4; 0 fetch USDC, 1 attention slot).
Preview includes a trade-off table explicitly stating SKIP LOCKED does NOT solve stalled/crashed workers, deduplication, or exactly-once delivery — directly answers crash and idempotency gap claims 4 and 5, plus claim 0. - free public original-page READ selection (not a cache hit); no purchase or creator reward. — selected for the claim-aware evidence portfolio (targets claims 1, 5, 6; 0 fetch USDC, 1 attention slot).
Preview shows locking clauses, SKIP LOCKED skip behavior, the inconsistent-view trade-off, and a naive race example — supports claims 0,1,2,3. - free public original-page READ selection (not a cache hit); no purchase or creator reward. — the claim-aware portfolio chose a stronger, less redundant set inside the 4-source attention and $0.015000 fetch-budget caps, so this proposal stays unspent.
Preview explicitly contrasts normal SELECT FOR UPDATE waiting vs SKIP LOCKED, explains intentional inconsistency, unsuitability for general queries, and queue-like suitability — strong for claims 0,1,2,3. - free public original-page READ selection (not a cache hit); no purchase or creator reward. — the claim-aware portfolio chose a stronger, less redundant set inside the 4-source attention and $0.015000 fetch-budget caps, so this proposal stays unspent.
Preview gives a concrete naive normal-SELECT double-claim race and explains SKIP LOCKED's skip semantics — directly supports claims 1 and 0. - free public original-page READ selection (not a cache hit); no purchase or creator reward. — the claim-aware portfolio chose a stronger, less redundant set inside the 4-source attention and $0.015000 fetch-budget caps, so this proposal stays unspent.
Preview covers SKIP LOCKED locking/skipping, concurrent worker claims, one-transaction claim+update, and idempotency keys for at-least-once delivery — supports claims 0,1,5. - free public original-page READ selection (not a cache hit); no purchase or creator reward. — the claim-aware portfolio chose a stronger, less redundant set inside the 4-source attention and $0.015000 fetch-budget caps, so this proposal stays unspent.
Preview is a fragmentary cleanup DELETE snippet with no usable content on SKIP LOCKED, normal SELECT, inconsistent view, queue semantics, crash, or idempotency; no sub-claim can be investigated. - free public original-page READ selection (not a cache hit); no purchase or creator reward.
Preview frames the naive SELECT-then-UPDATE race between two workers, supporting the normal-SELECT comparison in claim 1. - free public original-page READ selection (not a cache hit); no purchase or creator reward. — the claim-aware portfolio chose a stronger, less redundant set inside the 4-source attention and $0.015000 fetch-budget caps, so this proposal stays unspent.
Preview explains SKIP LOCKED's purpose for concurrent work queues and how plain row locking serializes workers, supporting claims 0 and 1. - free public original-page READ selection (not a cache hit); no purchase or creator reward. — the claim-aware portfolio chose a stronger, less redundant set inside the 4-source attention and $0.015000 fetch-budget caps, so this proposal stays unspent.
Preview describes SKIP LOCKED locking/skipping, atomic claim+status flip in one transaction, and non-blocking concurrent workers — supports claims 0 and 1. - free public original-page READ selection (not a cache hit); no purchase or creator reward. — the claim-aware portfolio chose a stronger, less redundant set inside the 4-source attention and $0.015000 fetch-budget caps, so this proposal stays unspent.
Preview explains SKIP LOCKED as a FOR UPDATE modifier that skips locked rows without waiting, ideal for multiple queue workers — supports claims 0 and 1. - free public original-page READ selection (not a cache hit); no purchase or creator reward. — the claim-aware portfolio chose a stronger, less redundant set inside the 4-source attention and $0.015000 fetch-budget caps, so this proposal stays unspent.
Preview demonstrates normal FOR UPDATE serializing two workers and introduces SKIP LOCKED bypassing that, supporting claims 0 and 1. - free public original-page READ selection (not a cache hit); no purchase or creator reward. — the claim-aware portfolio chose a stronger, less redundant set inside the 4-source attention and $0.015000 fetch-budget caps, so this proposal stays unspent.
Preview shows a SKIP LOCKED claim transaction and a real-world duplicate-assignment symptom, relevant to claims 0 and 5. - free public original-page READ selection (not a cache hit); no purchase or creator reward. — the claim-aware portfolio chose a stronger, less redundant set inside the 4-source attention and $0.015000 fetch-budget caps, so this proposal stays unspent.
Hacker News comment fragment shows a plain SELECT FOR UPDATE with attempts/status, but no SKIP LOCKED, inconsistent-view, or crash/idempotency analysis; weak and largely redundant. - free public original-page READ selection (not a cache hit); no purchase or creator reward.
Preview states SKIP LOCKED prevents duplicate claims but is insufficient beyond that, directly relevant to the idempotency gap in claim 5. - free public original-page READ selection (not a cache hit); no purchase or creator reward. — the claim-aware portfolio chose a stronger, less redundant set inside the 4-source attention and $0.015000 fetch-budget caps, so this proposal stays unspent.
Official explicit-locking docs excerpt explains FOR UPDATE lock semantics and blocking behavior, grounding the normal-SELECT comparison in claim 1. - free public original-page READ selection (not a cache hit); no purchase or creator reward. — the claim-aware portfolio chose a stronger, less redundant set inside the 4-source attention and $0.015000 fetch-budget caps, so this proposal stays unspent.
Generic SELECT tutorial covering DISTINCT/ORDER BY/joins; no locking, SKIP LOCKED, inconsistent-view, crash, or idempotency content for any sub-claim. - free public original-page READ selection (not a cache hit); no purchase or creator reward.
Preview is only a generic SELECT grammar sketch with FOR UPDATE/SHARE/NOWAIT but no SKIP LOCKED, queue, inconsistent-view, crash, or idempotency discussion. - free public original-page READ selection (not a cache hit); no purchase or creator reward.
Stack Overflow question about what data a SELECT returns; irrelevant to locking, queue claiming, inconsistent views, crash, or idempotency. - free public original-page READ selection (not a cache hit); no purchase or creator reward.
General query-processing/MVCC overview with no SKIP LOCKED, queue-claim, inconsistent-view, crash, or idempotency specifics. - free public original-page READ selection (not a cache hit); no purchase or creator reward.
Preview contrasts NOWAIT/WAIT/SKIP LOCKED and notes SKIP LOCKED is useful for queue tables with multiple consumers, supporting claims 0 and 1. - free public original-page READ selection (not a cache hit); no purchase or creator reward. — the claim-aware portfolio chose a stronger, less redundant set inside the 4-source attention and $0.015000 fetch-budget caps, so this proposal stays unspent.
Preview covers SELECT FOR UPDATE vs FOR SHARE row locking generally but not SKIP LOCKED, inconsistent views, queue claiming, crash, or idempotency. - free public original-page READ selection (not a cache hit); no purchase or creator reward.
READ Building a PostgreSQL Job Queue with FOR UPDATE SKIP LOCKED | Akshay Gupta - selected original public page, 0 USDC; not a cache hit.
Public page unavailable (html-extraction-unavailable); no evidence admitted. Continuing research.
READ Build a PostgreSQL worker queue with SKIP LOCKED - selected original public page, 0 USDC; not a cache hit.
Read extracted public text from https://jpcasabianca.com/journal/build-postgres-worker-queue-with-skip-locked/ - S1; quote matching establishes source grounding, not fact verification.
READ Postgres SELECT FOR UPDATE SKIP LOCKED: Job Queues – Chat2DB - selected original public page, 0 USDC; not a cache hit.
Read extracted public text from https://chat2db.ai/resources/blog/postgres-select-for-update-skip-locked - S2; quote matching establishes source grounding, not fact verification.
READ SELECT ... FOR UPDATE SKIP LOCKED: The Right Way to Build a Concurrent Job Queue in PostgreSQL | QueryStack - selected original public page, 0 USDC; not a cache hit.
Public page unavailable (html-extraction-unavailable); no evidence admitted. Continuing research.
Sub-claim "According to https://www.postgresql.org/docs/current/sql-sel…": 50% covered by S1, S2 — S1 states SKIP LOCKED is useful for multiple consumers accessing a queue-like table and gives a claim outline (select ready work with FOR UPDATE SKIP LOCKED, assign lease owner/expiry, commit). S2 explains SKIP LOCKED treats locked rows as if they did not exist for this statement, so each worker sees a different subset of available rows, and that lock/update should be in one short transaction. However, neither source is the PostgreSQL SELECT documentation itself, and the passages do not fully specify the exact documented behavior for three workers.
Sub-claim "According to https://www.postgresql.org/docs/current/sql-sel…": 20% covered by S2 — S2 contrasts SKIP LOCKED with NOWAIT and describes SKIP LOCKED as giving something else, but the supplied passages do not directly describe a normal SELECT claim race or its behavior with three workers. This is only topical context.
Sub-claim "According to https://www.postgresql.org/docs/current/sql-sel…": 60% covered by S1, S2 — S1 says PostgreSQL documents that SKIP LOCKED provides an inconsistent view unsuitable for general queries but useful for multiple consumers accessing a queue-like table. S2 says the documentation is explicit that SKIP LOCKED yields an inconsistent view and that this is intentional for a queue. This partially answers the caveat and its queue application, but the supplied passages do not fully explain how the caveat differs from a normal SELECT.
Sub-claim "According to https://www.postgresql.org/docs/current/sql-sel…": 60% covered by S1, S2 — S1 states SKIP LOCKED is unsuitable for general queries but useful for multiple consumers accessing a queue-like table. S2 says for a queue an inconsistent view is exactly what you want because each worker should see a different subset of available rows. This gives the core distinction, but not a full documented explanation.
Sub-claim "According to https://www.postgresql.org/docs/current/sql-sel…": 30% covered by S1, S2 — S1 lists worker crash after claiming and says the queue needs leases, idempotent handlers, retry policy, terminal states, indexes, and observable recovery; S2 mentions a visibility timeout sweeper for crashed workers. These are topical context about crash handling, but the supplied passages do not identify which crash questions the SELECT documentation specifically does not resolve.
Sub-claim "According to https://www.postgresql.org/docs/current/sql-sel…": 30% covered by S1, S2 — S1 mentions repeat a side effect after losing a response and says the queue needs idempotent handlers; S2 says the dequeue must still be the source of truth. These are topical context, but the supplied passages do not identify which idempotency questions the SELECT documentation specifically does not resolve.
Coverage is partial across most sub-claims, but the remaining budget is only 0.015 and no skipped source is affordable. The gathered passages provide useful queue context but do not fully substitute for the PostgreSQL SELECT documentation, especially for normal SELECT behavior, crash questions, and idempotency questions.
Final check — "According to https://www.postgresql.org/docs/current/sql-sel…": 40% assessed by S1, S2
Final check — "According to https://www.postgresql.org/docs/current/sql-sel…": 20% assessed by S2
Final check — "According to https://www.postgresql.org/docs/current/sql-sel…": 40% assessed by S1, S2
Final check — "According to https://www.postgresql.org/docs/current/sql-sel…": 40% assessed by S1, S2
Final check — "According to https://www.postgresql.org/docs/current/sql-sel…": 20% assessed by S1, S2
Final check — "According to https://www.postgresql.org/docs/current/sql-sel…": 20% assessed by S1
Final coverage assessment — The supplied passages are excerpts from two third-party articles, not from the requested PostgreSQL SELECT documentation page. They provide topical context and some direct statements about SKIP LOCKED, inconsistent views, queue-like use, and crash/idempotency concerns, but they do not supply the requested documentation-based comparison, decision table, transaction outline, or explicit list of unresolved crash/idempotency questions. Coverage is therefore low to partial across all sub-claims. The assessment does not establish a complete supported answer for every requested part.
Synthesizing a grounded answer from 2 source(s)…
Relevance review returned; only checked excerpts can retain support, and review cannot raise it.
Delivering qualified source excerpts; complete synthesis and per-assertion support remain unverified.
Source-matched public excerpt (no creator reward) — S2, research target 1, proposed support 90% (estimate, not entailment): “SKIP LOCKED (PostgreSQL 9.5 and later) is for "give me something else": it treats locked rows as if they did not exist for this statement.”
Source-matched public excerpt (no creator reward) — S2, research target 1, proposed support 70% (estimate, not entailment): “FOR UPDATE SKIP LOCKED turns an ordinary PostgreSQL table into a safe, concurrent job queue.”
Source-matched public excerpt (no creator reward) — S1, research target 1, proposed support 60% (estimate, not entailment): “Select ready work by schedule and priority with FOR UPDATE SKIP LOCKED, assign lease owner and expiry, then commit.”
Source-matched public excerpt (no creator reward) — S2, research target 3, proposed support 90% (estimate, not entailment): “The documentation is explicit that this yields an inconsistent view of the data, and that is intentional; for a queue, an inconsistent view …”
Source-matched public excerpt (no creator reward) — S1, research target 3, proposed support 80% (estimate, not entailment): “PostgreSQL documents that SKIP LOCKED provides an inconsistent view unsuitable for general queries but useful for multiple consumers accessi…”
Source-matched public excerpt (no creator reward) — S1, research target 4, proposed support 80% (estimate, not entailment): “PostgreSQL documents that SKIP LOCKED provides an inconsistent view unsuitable for general queries but useful for multiple consumers accessi…”
Source-matched public excerpt (no creator reward) — S2, research target 4, proposed support 80% (estimate, not entailment): “The documentation is explicit that this yields an inconsistent view of the data, and that is intentional; for a queue, an inconsistent view …”
Source-matched public excerpt (no creator reward) — S1, research target 5, proposed support 40% (estimate, not entailment): “A worker can crash after claiming, repeat a side effect after losing a response, starve old jobs behind priority traffic, hold a transaction…”
Source-matched public excerpt (no creator reward) — S1, research target 5, proposed support 40% (estimate, not entailment): “The queue needs leases, idempotent handlers, retry policy, terminal states, indexes, and observable recovery.”
Source-matched public excerpt (no creator reward) — S1, research target 6, proposed support 40% (estimate, not entailment): “The queue needs leases, idempotent handlers, retry policy, terminal states, indexes, and observable recovery.”
Source-matched public excerpt (no creator reward) — S1, research target 6, proposed support 40% (estimate, not entailment): “A worker can crash after claiming, repeat a side effect after losing a response, starve old jobs behind priority traffic, hold a transaction…”
Prepared source excerpts citing 2 source(s); complete synthesis is unverified
Confidence: Low — Only source excerpts are delivered; complete synthesis and per-assertion support remain unverified. Evidence assessment: 3 sub-claims remain below the evidence threshold.
jpcasabianca.com contributed 45% - free public reference; reward share withheld
chat2db.ai contributed 55% - free public reference; reward share withheld
Done. Spent $0 across 0 confirmed/simulated payment(s) to creators.
Portable research receipt
Take the evidence trail with you
One deterministic JSON bundle binds the answer, visible decisions, exact article versions, claim evidence and a Circle-settlement snapshot under SHA-256. Retain the digest to detect later changes; the self-check is not a publisher or Keryx signature.
Carries this dispatch’s question as context — never its answer. The next dispatch is read from sources bought for it.