feat: add introspection support to query metadata from sqlq

schema/v7.sql

@@ -0,0 +1,47 @@
+-- SQL migration to add introspection functions
+
+-- Function: sqlq.job_logs()
+--
+-- sqlq.job_logs() return all logs emitted by the job until time of invocation.
+CREATE FUNCTION sqlq.job_logs(id BIGINT)
+-- @formatter:off
+    RETURNS TABLE (ts TIMESTAMPTZ, level SQLQ.LOG_LEVEL, msg TEXT) AS
+-- @formatter:on
+$$
+BEGIN
+    RETURN QUERY
+        SELECT log.logged_at, log.level, log.message
+        FROM sqlq.job_logs log
+        WHERE log.job = id;
+END;
+$$ LANGUAGE plpgsql STABLE;
+
+-- Type: sqlq.queue_info
+--
+-- Used as return type of sqlq.queue_info(text) function below.
+CREATE TYPE sqlq.queue_info AS
+(
+    pending BIGINT, -- # of tasks in pending state
+    running BIGINT, -- # of tasks in running state
+    success BIGINT, -- # of tasks in success state
+    errored BIGINT  -- # of tasks in errored state
+);
+
+-- Function: sqlq.queue_info()
+--
+-- sqlq.queue_info() return details about the given queue.
+CREATE FUNCTION sqlq.queue_info(name TEXT) RETURNS sqlq.queue_info AS
+$$
+DECLARE
+    out sqlq.queue_info%rowtype;
+BEGIN
+    SELECT INTO out SUM(CASE WHEN status = 'pending' THEN 1 ELSE 0 END) AS pending,
+                    SUM(CASE WHEN status = 'running' THEN 1 ELSE 0 END) AS running,
+                    SUM(CASE WHEN status = 'success' THEN 1 ELSE 0 END) AS success,
+                    SUM(CASE WHEN status = 'errored' THEN 1 ELSE 0 END) AS errored
+    FROM sqlq.jobs
+    WHERE queue = name;
+
+    RETURN out;
+END;
+$$ LANGUAGE plpgsql STABLE;