Method init

core/src/main/java/io/questdb/Telemetry.java:141–207

(CairoEngine engine, SqlCompiler compiler, SqlExecutionContext sqlExecutionContext)

    }

    public void init(CairoEngine engine, SqlCompiler compiler, SqlExecutionContext sqlExecutionContext) throws SqlException {
        if (!enabled) {
            return;
        }
        String tableName = telemetryType.getTableName();
        boolean shouldDropTable = false;
        boolean shouldAlterTtl = false;
        TableToken tableToken = null;
        try {
            tableToken = engine.verifyTableName(tableName);
            try (TableMetadata meta = engine.getTableMetadata(tableToken)) {
                int ttl = meta.getTtlHoursOrMonths();
                if (ttl == 0) {
                    shouldDropTable = true;
                } else if (ttlWeeks > 0 && ttl > 0 && ttl != ttlWeeks * 24 * 7) {
                    shouldAlterTtl = true;
                }
                // Drop and recreate when schema changes (safe for short-TTL telemetry tables).
                // Note: uses != rather than <, so a rollback to older code will also re-drop.
                int expectedColumnCount = telemetryType.getExpectedColumnCount();
                if (expectedColumnCount > 0 && meta.getColumnCount() != expectedColumnCount) {
                    shouldDropTable = true;
                }
            }
        } catch (CairoException e) {
            if (!Chars.contains(e.getFlyweightMessage(), "table does not exist")) {
                throw e;
            }
        }
        if (shouldDropTable) {
            compiler.query().$("DROP TABLE '").$(tableName).$("'")
                    .compile(sqlExecutionContext)
                    .getOperation()
                    .execute(sqlExecutionContext, null)
                    .await();
        } else if (shouldAlterTtl) {
            assert tableToken != null;
            try (MetadataCacheWriter metadataRW = engine.getMetadataCache().writeLock()) {
                metadataRW.hydrateTable(tableToken);
            }
            compiler.query().$("ALTER TABLE '").$(tableName).$("' SET TTL ").$(ttlWeeks).$(" WEEKS")
                    .compile(sqlExecutionContext)
                    .execute(null)
                    .await();
        }
        telemetryType.getCreateSql(compiler.query(), ttlWeeks).createTable(sqlExecutionContext);
        tableToken = engine.verifyTableName(tableName);
        try {
            writer = engine.getWriter(tableToken, "telemetry");
        } catch (CairoException ex) {
            LOG.error()
                    .$("could not open [table=").$(tableToken)
                    .$(", msg=").$safe(ex.getFlyweightMessage())
                    .$(", errno=").$(ex.getErrno())
                    .$(']').$();
        }

        telemetryType.logStatus(writer, TelemetryEvent.SYSTEM_UP, clock.getTicks());