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diff --git a/notes/2021_09_review.md b/notes/2021_09_review.md
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+# Fuzzy matching review and retrospective
+
+> 2021-09-15
+
+After [refcat](https://gitlab.com/internetarchive/refcat) has reached a
+milestone, I'd like to review fuzzycat and fuzzy matching in general; this
+should help pave the way to a slight redesign of the overall approach.
+
+## TL;DR
+
+* performance matters at scale and a faster language (e.g. Go) is essential
+* for small scale, the api matters more than performance
+* a lot of the code currently is base on specific schemas (e.g. release, a
+  specific elasticsearch mapping, etc), so not that much code is generic or
+  reusable - it also seems overkill to try to abstract the schema away
+
+## Ideas
+
+* [ ] use pydantic or dataclass to make schema more explicit
+* [ ] extend type annotation coverage
+* [ ] remove bulk stuff, remove clustering etc; improve the verification part
+* [ ] use cases: work merging
+
+A few more things to revisit:
+
+* [ ] revisit journal matching; what is weak, strong?
+* [ ] refactor: author list or string comparison
+* [ ] go beyond title matching when querying elasticsearch
+* [ ] better container name matching
+
+Take a look at:
+
+> https://github.com/djudd/human-name
+
+----
+
+## Redesign ideas
+
+### Large scale processing
+
+JSON decoding and encoding does not seem to be the bottleneck, but working with
+various, often optional fields gets expensive in Python (whereas in Go, we can
+use a struct).
+
+The mapping stage in
+[refcat/skate](https://gitlab.com/internetarchive/refcat/-/blob/3a79551dfe54ba668f7eee9de88625a0d33d9c7f/skate/map.go#L109-111)
+is a simple operation (blob to fields), that can be implemented in isolation
+and then [added to the command
+line](https://gitlab.com/internetarchive/refcat/-/blob/3a79551dfe54ba668f7eee9de88625a0d33d9c7f/skate/cmd/skate-map/main.go#L67-87).
+In skate, we already have over a dozen mappers working on various types.
+There's even a bit of [map
+middleware](https://gitlab.com/internetarchive/refcat/-/blob/3a79551dfe54ba668f7eee9de88625a0d33d9c7f/skate/map.go#L152-161).
+
+In fuzzycat, the
+[Cluster](https://git.archive.org/webgroup/fuzzycat/-/blob/c587a084defe54103aa147b7ab91542a11a548b1/fuzzycat/cluster.py#L309-347)
+class does mapping, via
+[key](https://git.archive.org/webgroup/fuzzycat/-/blob/c587a084defe54103aa147b7ab91542a11a548b1/fuzzycat/cluster.py#L331),
+[sorting](https://git.archive.org/webgroup/fuzzycat/-/blob/c587a084defe54103aa147b7ab91542a11a548b1/fuzzycat/cluster.py#L406-426),
+and a specific
+[grouping](https://git.archive.org/webgroup/fuzzycat/-/blob/c587a084defe54103aa147b7ab91542a11a548b1/fuzzycat/cluster.py#L428-454)
+all in one go.
+
+For example, we did not use the single cluster document in refcat/skate anymore
+(there, we keep two separate files and use an extra
+[zipkey](https://gitlab.com/internetarchive/refcat/-/blob/3a79551dfe54ba668f7eee9de88625a0d33d9c7f/skate/zipkey/zipkey.go#L23-33)
+type, which is a slightly generalized
+[comm](https://en.wikipedia.org/wiki/Comm), e.g. it allows to run a function
+over a cluster of documents (coming from currently two streams).
+
+A higher level command could encapsulate the whole pipeline, without needed an extra framework like luigi:
+
+    inputs     A   B
+               |   |
+    mapped     M1  M2
+               |   |
+    sorted     S1  S2
+               \   /
+                \ /
+    reduced      V
+                 |
+                 |
+                 C
+
+> Not sure, if we need mappers at all, if we have them in refcat.
+
+An a command could look like this.
+
+    $ fuzzycat pipeline -a A.json -b B.json --mapper-a "tn" --mapper-b "tn" --reduce "bref"
+
+Nice, if this would actually run fast. Could also be run programmatically:
+
+    output = fuzzycat_pipeline(a="A.json", b="B.json", mapper_a="tn", mapper_b="tn", reduce="bref")
+
+Mappers should have a minimal scope; each mapper will have a format it can work
+on. Reducers will have two inputs types specified.
+
+### Running continuously
+
+> With a couple of the inputs (metadata, extracted data, ...) getting updated
+> all the time, it might for the moment be simpler to rerun the derivation in
+> batch mode.
+
+A list of steps we would need to implement for continuous reference index updates:
+
+* a new metadata document arrives (e.g. via "changelog")
+* if the metadata contains outbound references, nice; if not, we try to download the associated PDF, run grobid and get the references out that way
+
+At this point, we have the easier part - outbound references - covered.
+
+Where do the outbound references of all existing docs live? In the database
+only, hence we cannot search for them currently.
+
+* [7ppmkfo5krb2zhefhwkwdp4mqe](https://search.fatcat.wiki/fatcat_release/_search?q=ident:7ppmkfo5krb2zhefhwkwdp4mqe)
+  says `ref_count` 12, but the list of refs we can only get via
+  [api](https://api.fatcat.wiki/v0/release/7ppmkfo5krb2zhefhwkwdp4mqe)
+
+We could add another elasticsearch index only for the raw refs. E.g. everytime
+an item is updated, this index gets updated as well (taking refs from the API
+and put them into ES). We can then query for any ID we find in the reference or
+any string match, etc. Once we find e.g. ten documents, that have the document
+in question in their reference list, we can update the reference index for each
+of these documents.
+
+We could keep a (weekly) refs snapshot file around that would be used for
+matching. The result would be the e.g. ten document, that refer to the document
+in question. We can take their ids and update the document to establish the
+link. The on-disk file (or files) should be all prepared, e.g. sorted by key,
+so the lookup will be fast.
+
diff --git a/notes/Makefile b/notes/Makefile
index 3a7dcaf..b4996f9 100644
--- a/notes/Makefile
+++ b/notes/Makefile
@@ -1,6 +1,11 @@
-steps.png: steps.dot
+TARGETS = workflow_schema.png
+
+.PHONY: all
+all: $(TARGETS)
+
+%.png: %.dot
 	dot -Tpng $^ > $@
 
 .PHONY: clean
 clean:
-	rm -rf steps.png
+	rm -rf $(TARGETS)
diff --git a/notes/known_issues.md b/notes/known_issues.md
index 32194fd..991de5c 100644
--- a/notes/known_issues.md
+++ b/notes/known_issues.md
@@ -102,3 +102,20 @@ $ python -m fuzzycat verify_single | jq .
   ]
 }
 ```
+
+## "jaccard authors" can be too weak
+
+```
+$ python -m fuzzycat verify_single | jq .
+{
+  "extra": {
+    "q": "https://fatcat.wiki/release/search?q=canes"
+  },
+  "a": "https://fatcat.wiki/release/ivhoiqvjt5cpxbdzzbuco7eciq",
+  "b": "https://fatcat.wiki/release/hprvn76ls5cbbkl2ypsyijojmu",
+  "r": [
+    "strong",
+    "jaccard_authors"
+  ]
+}
+```
diff --git a/notes/todo.md b/notes/todo_manual_review.md
index b3474f8..b3474f8 100644
--- a/notes/todo.md
+++ b/notes/todo_manual_review.md
diff --git a/notes/steps.dot b/notes/workflow_schema.dot
index 365163f..365163f 100644
--- a/notes/steps.dot
+++ b/notes/workflow_schema.dot
diff --git a/notes/steps.png b/notes/workflow_schema.png
index b321976..b321976 100644
--- a/notes/steps.png
+++ b/notes/workflow_schema.png