tweaks to PDB and BPlusTree constants, a=chris

diff --git a/src/configs/Config.php b/src/configs/Config.php
index 61b985612..943deeca1 100755
--- a/src/configs/Config.php
+++ b/src/configs/Config.php
@@ -757,7 +757,7 @@ nsconddefine('URL_FILTER_SIZE', MEMORY_PROFILE * 5000000);
  */
 nsconddefine('NUM_URLS_QUEUE_RAM', MEMORY_PROFILE * 80000);
 /** number of documents before next gen */
-nsconddefine('NUM_DOCS_PER_PARTITION', MEMORY_PROFILE * 10000);
+nsconddefine('NUM_DOCS_PER_PARTITION', 6 * MEMORY_PROFILE * 10000);
 /** precision to round floating points document scores */
 nsconddefine('PRECISION', 10);
 /** maximum number of links to extract from a page on an initial pass*/
diff --git a/src/library/BPlusTree.php b/src/library/BPlusTree.php
index e468af298..298803563 100644
--- a/src/library/BPlusTree.php
+++ b/src/library/BPlusTree.php
@@ -46,7 +46,7 @@ class BPlusTree
      * The MAXIMUM number of keys stored in a tree node (will split if have
      * more)
      */
-    const MAX_KEYS = 1001;
+    const MAX_KEYS = 2001;
     /**
      *
      */
diff --git a/src/library/IndexDocumentBundle.php b/src/library/IndexDocumentBundle.php
index f08bbf5b1..62d9b7f86 100644
--- a/src/library/IndexDocumentBundle.php
+++ b/src/library/IndexDocumentBundle.php
@@ -187,6 +187,9 @@ class IndexDocumentBundle implements CrawlConstants
             $num_docs_per_partition,
             PartitionDocumentBundle::PARTITION_SIZE_THRESHOLD,
             C\NS_COMPRESSORS . "GzipCompressor");
+        if (!$read_only_archive) {
+            $this->documents->index_cache_size = 1;
+        }
         $this->doc_map_tools = new PackedTableTools([
             "PRIMARY KEY" => ["DOC_KEYS", 24], "POS" => "INT",
             "SCORE" => "FLOAT"], C\NS_COMPRESSORS . "GzipCompressor");
diff --git a/src/library/PackedTableTools.php b/src/library/PackedTableTools.php
index 20245c719..3851eae7c 100644
--- a/src/library/PackedTableTools.php
+++ b/src/library/PackedTableTools.php
@@ -171,7 +171,6 @@ class PackedTableTools
                 return null;
             }
             $this->format[$field_name] = $type_synonyms[$type];
-            $unpack_name = $field_name;
             if ($type == "BOOL") {
                 $this->num_bool_columns++;
             } else if ($type == "INT") {
diff --git a/src/library/PartitionDocumentBundle.php b/src/library/PartitionDocumentBundle.php
index df28fe1e8..76a0145df 100644
--- a/src/library/PartitionDocumentBundle.php
+++ b/src/library/PartitionDocumentBundle.php
@@ -66,7 +66,7 @@ class PartitionDocumentBundle
     /**
      *
      */
-    const INDEX_CACHE_SIZE = 10;
+    const INDEX_CACHE_SIZE = 15;
     /**
      *
      */