Add ancestors_* tables, for faster 'toroot' lookupancestors-tables

Speedup seemed minor, and for a non-wide range of situations.
It also roughly quadrupled the database size.

1 files changed, 5 insertions, 4 deletions

diff --git a/backend/data/README.md b/backend/data/README.md
index 13aeb89..b4b0745 100644
--- a/backend/data/README.md
+++ b/backend/data/README.md
@@ -43,6 +43,8 @@ This directory holds files used to generate data.db, which contains tree-of-life
     These are like `nodes`, but describe the nodes for various reduced trees.
 -   `edges_t`, `edges_i`, `edges_p` <br>
     Like `edges` but for reduced trees.
+-   `ancestors_t`, `ancestors_i`, `ancestors_p` <br>
+    Maps nodes to their ancestors. Used for faster lookup.
 
 # Generating the Database
 
@@ -146,7 +148,6 @@ Some of the python scripts require third-party packages:
         These correspond to entries in the `names` table. `prefAlt` should be 1 or 0.
         A line like `name1|name1|1` causes a node to have no preferred alt-name.
 3.  Run genReducedTrees.py, which generates multiple reduced versions of the tree,
-    adding the `nodes_*` and `edges_*` tables, using `nodes` and `names`. Reads from
-    pickedNodes.txt, which lists names of nodes that must be included (1 per line).
-    The original tree isn't used for web-queries, as some nodes would have over 
-    10k children, which can take a while to render (took over a minute in testing).
+    adding the `nodes_*`, `edges_*`, and `ancestors_*` tables, using `nodes` and
+    `names`. Reads from pickedNodes.txt, which lists names of nodes that must be
+    included (1 per line). The original tree isn't used for web-queries.