feat(join): consume numeric expression MAPs in bounded join pipelines

CHANGELOG.md

@@ -19,6 +19,17 @@ All notable changes to wirelog are documented in this file.
 
 ### Changed
 
+- **Bounded join pipelines consume expression MAPs** (#1777): with
+  `WIRELOG_JOIN_BATCH_BYTES` set, a `JOIN -> FILTER* -> MAP` pipeline
+  whose MAP computes integer or float arithmetic or comparisons is now
+  evaluated batch by batch instead of materializing the whole join first;
+  previously only projection MAPs qualified.  String, digest, UUID,
+  aggregate and extension expressions still fall back to the one-shot
+  join (`ENOTSUP` under `WIRELOG_JOIN_BATCH_STRICT=1`).  A FILTER or MAP
+  failure inside the pipeline now returns that operator's errno -- for
+  MAP, `ERANGE` for an expression error and `ENOSPC` for a denied
+  admission -- where every such failure previously became `ENOMEM`.
+
 - **Bounded join scratch is sized lazily** (#1481):
   `col_join_batch_producer_create` reserved `WIRELOG_JOIN_BATCH_BYTES /
   row_bytes` rows of governed scratch at create, whatever the join's

docs/MEMORY.md

@@ -1219,8 +1219,22 @@ join; the session records the fallback count and last reason and logs one
 `JOIN` warning per reason.  `WIRELOG_JOIN_BATCH_STRICT=1` (ignored unless
 the bytes knob is set) turns a fallback into an `ENOTSUP` failure, which is
 the explicit bounded-mode result for unsupported shapes.  Differential
-keyed joins have the separate producer described below; pipeline consumption
-of batches on the eval stack (JOIN -> FILTER* -> MAP) remains #1475.
+keyed joins have the separate producer described below.
+
+A non-differential eligible join followed by `FILTER* -> MAP` is consumed
+batch by batch on the eval stack (#1475), so the full join intermediate is
+not materialized while the pipeline runs: each batch is filtered and mapped
+into one output relation, which is published only after the last batch.  The
+FILTERs may use only numeric variables, numeric and boolean literals, and
+comparisons.  The MAP may project columns or evaluate numeric expressions --
+integer and float arithmetic and comparisons (#1777).  A MAP with a string,
+digest, UUID, aggregate or extension expression is not consumed; those have
+no batch contract yet.  A JOIN whose downstream operators are not
+consumable, or whose input goes stale mid-stream, falls back to the one-shot
+join with reason `pipeline-not-consumable` (`ENOTSUP` under
+`WIRELOG_JOIN_BATCH_STRICT=1`).  A FILTER or MAP failure inside the pipeline
+returns that operator's errno -- for MAP, `ERANGE` for a failed expression
+and `ENOSPC` for a denied admission -- and publishes no rows.
 
 Ownership and admission:
 

tests/meson.build

@@ -2069,6 +2069,7 @@ test_join_pipeline_exe = executable(
   'test_join_pipeline',
   files('test_join_pipeline.c'),
   include_directories: [wirelog_inc, wirelog_src_inc],
+  c_args: ['-DWL_SESSION_TEST_HOOKS=1'],
   dependencies: [nanoarrow_dep, threads_dep, xxhash_dep, mbedtls_dep, math_dep],
   link_with: [testlib_prod],
 )