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Get a PostgreSQL connection string

This operation returns a fully formatted PostgreSQL connection string. Unlike SQL Server and Oracle, the PostgreSQL host is not managed by the DBConnectionAPI: the API returns a template with a {SERVER} placeholder, and this operation substitutes the caller-supplied server after retrieval.

Field Value
Operation ID OP-DBC-04
Trigger Caller invokes GetPostgreSqlServerConnection(server, instance, userName)
Inputs server (host), instance, userName
Outputs Full PostgreSQL connection string with the host substituted
Primary components ConnectionClient.GetPostgreSqlServerConnection
Entry point src/SAIF.NetCore.DbConnectionClient/SAIF.NetCore.DBConnectionClient/SAIF.NetCore.DBConnectionClient/ConnectionClient.cs

Steps

  1. Build the cache key POSTGRES_{instance}_{userName} — note that server is not part of the key (BR-DBC-04, BR-DBC-05).
  2. Build the URL path /{PostgreSqlEndpoint}/{instance}/{userName} — server is not sent to the API (BR-DBC-05).
  3. Acquire the instance-wide connection-string lock and check the cache for this key. On a cache hit, release the lock and skip to step 5 with the cached template.
  4. On a cache miss (still under the lock): validate the backoff configuration, then call HttpClient.GetAsync(urlPath) in a loop of up to MaxRetrieveAttempts (4, by default). A successful non-empty response is decoded, cached (as the un-substituted template — server is not part of the cached value), and used below. HTTP 401/403/404 fail fast with no retry (BR-DBC-09). A 503 or network-level error is transient and retries with fixed backoff (2s, 3s, 5s) until attempts are exhausted (BR-DBC-10). Any other non-success or an empty body fails immediately (BR-DBC-11). A failed attempt is never cached; the lock is released once the outcome (value or exception) is determined.

  5. Origin: Steps 3.1–3.5 of Cached lookup, which embed the retry and classification logic from Retrieve with retry, are executed on behalf of this operation.

  6. Replace the literal {SERVER} placeholder in the template with the caller-supplied server (BR-DBC-05).
  7. Because the cache holds the un-substituted template, different hosts sharing the same instance and user reuse a single fetch.

Process flow

flowchart TD
    Start([GetPostgreSqlServerConnection called]) --> Key["Build key POSTGRES_instance_userName, no server"]
    Key --> Path[Build URL path /PostgreSqlEndpoint/instance/userName]
    Path --> Lock["Acquire lock, check cache"]
    Lock --> Hit{Cache hit?}
    Hit -->|Yes| Substitute
    Hit -->|No| Get["GetAsync, up to 4 attempts"]
    Get --> Outcome{Outcome}
    Outcome -->|Success| Substitute["Replace literal SERVER placeholder with caller server"]
    Outcome -->|"401/403/404"| FailFast(["Throw DBClientException, no retry"])
    Outcome -->|"503/network error"| Retry["Backoff 2s/3s/5s, retry or throw"]
    Outcome -->|Other failure| ImmediateFail(["Throw DBClientException"])
    Substitute --> Return([Return connection string])

Failure and edge-case behavior

  • If the returned template has no {SERVER} placeholder, String.Replace leaves the string unchanged; this library does not validate the host or the final connection-string structure, so a template that already embeds a literal host would still be returned as-is, while one that genuinely omits the host would return a connection string missing it*.
  • Any exception from the underlying cached lookup propagates to the caller unchanged.

Note: Statements marked with * were inferred from code structure, naming conventions, or contextual evidence where direct confirmation was not available in source artifacts.

Sources

  • src/SAIF.NetCore.DbConnectionClient/SAIF.NetCore.DBConnectionClient/SAIF.NetCore.DBConnectionClient/ConnectionClient.cs