X-Git-Url: http://git.indexdata.com/?a=blobdiff_plain;f=isamb%2Fisamb.c;h=2ac59fb7c94de153cdedc72794d92b7fb3057ed9;hb=0d4ce8fe167ca3df0c216179de0a2e9d22ce3a6a;hp=706d0df18a3d476f4c80ee6213390dd5e95a2cc9;hpb=0b366aebe8bbba8de457b4b2d9571cbf2dd43352;p=idzebra-moved-to-github.git

diff --git a/isamb/isamb.c b/isamb/isamb.c
index 706d0df..2ac59fb 100644
--- a/isamb/isamb.c
+++ b/isamb/isamb.c
@@ -1,9 +1,26 @@
-/*
- *  Copyright (c) 1995-1998, Index Data.
- *  See the file LICENSE for details.
- *
- *  $Id: isamb.c,v 1.4 2002-04-17 08:17:13 adam Exp $
- */
+/* $Id: isamb.c,v 1.23 2003-03-02 23:12:50 adam Exp $
+   Copyright (C) 1995,1996,1997,1998,1999,2000,2001,2002,2003
+   Index Data Aps
+
+This file is part of the Zebra server.
+
+Zebra is free software; you can redistribute it and/or modify it under
+the terms of the GNU General Public License as published by the Free
+Software Foundation; either version 2, or (at your option) any later
+version.
+
+Zebra is distributed in the hope that it will be useful, but WITHOUT ANY
+WARRANTY; without even the implied warranty of MERCHANTABILITY or
+FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+for more details.
+
+You should have received a copy of the GNU General Public License
+along with Zebra; see the file LICENSE.zebra.  If not, write to the
+Free Software Foundation, 59 Temple Place - Suite 330, Boston, MA
+02111-1307, USA.
+*/
+
+#include <string.h>
 #include <yaz/xmalloc.h>
 #include <yaz/log.h>
 #include <isamb.h>
@@ -13,17 +30,33 @@ struct ISAMB_head {
     int first_block;
     int last_block;
     int block_size;
+    int block_max;
+    int free_list;
 };
 
 #define ISAMB_DATA_OFFSET 3
 
-#define DST_BUF_SIZE 4500
 #define DST_ITEM_MAX 256
 
+/* approx 2*4 K + max size of item */
+#define DST_BUF_SIZE 8448
+
+#define ISAMB_CACHE_ENTRY_SIZE 4096
+
+struct ISAMB_cache_entry {
+    ISAMB_P pos;
+    char *buf;
+    int dirty;
+    int hits;
+    struct ISAMB_cache_entry *next;
+};
+
+
 struct ISAMB_file {
     BFile bf;
     int head_dirty;
     struct ISAMB_head head;
+    struct ISAMB_cache_entry *cache_entries;
 };
 
 struct ISAMB_s {
@@ -32,22 +65,31 @@ struct ISAMB_s {
 
     struct ISAMB_file *file;
     int no_cat;
+    int cache; /* 0=no cache, 1=use cache, -1=dummy isam (for testing only) */
+    int log_io;        /* log level for bf_read/bf_write calls */
+    int log_freelist;  /* log level for freelist handling */
 };
 
 struct ISAMB_block {
-    int pos;
+    ISAMB_P pos;
     int cat;
     int size;
     int leaf;
     int dirty;
+    int deleted;
     int offset;
-    unsigned char *bytes;
+    char *bytes;
+    unsigned char *buf;
     void *decodeClientData;
+    int log_rw;
 };
 
 struct ISAMB_PP_s {
     ISAMB isamb;
+    ISAMB_P pos;
     int level;
+    int total_size;
+    int no_blocks;
     struct ISAMB_block **block;
 };
 
@@ -63,49 +105,158 @@ void decode_ptr (char **src, int *pos)
     (*src) += sizeof(*pos);
 }
 
-ISAMB isamb_open (BFiles bfs, const char *name, int writeflag, ISAMC_M method)
+ISAMB isamb_open (BFiles bfs, const char *name, int writeflag, ISAMC_M method,
+                  int cache)
 {
     ISAMB isamb = xmalloc (sizeof(*isamb));
-    int i, b_size = 64;
+    int i, b_size = 32;
 
     isamb->bfs = bfs;
     isamb->method = (ISAMC_M) xmalloc (sizeof(*method));
     memcpy (isamb->method, method, sizeof(*method));
     isamb->no_cat = 4;
+    isamb->log_io = 0;
+    isamb->cache = cache;
 
     isamb->file = xmalloc (sizeof(*isamb->file) * isamb->no_cat);
     for (i = 0; i<isamb->no_cat; i++)
     {
         char fname[DST_BUF_SIZE];
-        isamb->file[i].head.first_block = 1;
-        isamb->file[i].head.last_block = 1;
-        isamb->file[i].head.block_size = b_size;
-        b_size = b_size * 4;
+        isamb->file[i].cache_entries = 0;
+        isamb->file[i].head_dirty = 0;
+        sprintf (fname, "%s%c", name, i+'A');
+        if (cache)
+            isamb->file[i].bf = bf_open (bfs, fname, ISAMB_CACHE_ENTRY_SIZE,
+                                         writeflag);
+        else
+            isamb->file[i].bf = bf_open (bfs, fname, b_size, writeflag);
+
+        
+        if (!bf_read (isamb->file[i].bf, 0, 0, sizeof(struct ISAMB_head),
+                      &isamb->file[i].head))
+	{
+            isamb->file[i].head.first_block = ISAMB_CACHE_ENTRY_SIZE/b_size+1;
+            isamb->file[i].head.last_block = isamb->file[i].head.first_block;
+            isamb->file[i].head.block_size = b_size;
+            isamb->file[i].head.block_max = b_size - ISAMB_DATA_OFFSET;
+            isamb->file[i].head.free_list = 0;
+	}
+        assert (isamb->file[i].head.block_size >= ISAMB_DATA_OFFSET);
         isamb->file[i].head_dirty = 0;
-        sprintf (fname, "%s-%d", name, i);
-        isamb->file[i].bf =
-            bf_open (bfs, fname, isamb->file[i].head.block_size, writeflag);
-    
-        bf_read (isamb->file[i].bf, 0, 0, sizeof(struct ISAMB_head),
-                 &isamb->file[i].head);
+        assert(isamb->file[i].head.block_size == b_size);
+        b_size = b_size * 4;
     }
     return isamb;
 }
 
+static void flush_blocks (ISAMB b, int cat)
+{
+    while (b->file[cat].cache_entries)
+    {
+        struct ISAMB_cache_entry *ce_this = b->file[cat].cache_entries;
+        b->file[cat].cache_entries = ce_this->next;
+
+        if (ce_this->dirty)
+        {
+            yaz_log (b->log_io, "bf_write: flush_blocks");
+            bf_write (b->file[cat].bf, ce_this->pos, 0, 0, ce_this->buf);
+        }
+        xfree (ce_this->buf);
+        xfree (ce_this);
+    }
+}
+
+static int get_block (ISAMB b, ISAMC_P pos, char *userbuf, int wr)
+{
+    int cat = pos&3;
+    int off = ((pos/4) & 
+               (ISAMB_CACHE_ENTRY_SIZE / b->file[cat].head.block_size - 1))
+        * b->file[cat].head.block_size;
+    int norm = pos / (4*ISAMB_CACHE_ENTRY_SIZE / b->file[cat].head.block_size);
+    int no = 0;
+    struct ISAMB_cache_entry **ce, *ce_this = 0, **ce_last = 0;
+
+    if (!b->cache)
+        return 0;
+
+    assert (ISAMB_CACHE_ENTRY_SIZE >= b->file[cat].head.block_size);
+    for (ce = &b->file[cat].cache_entries; *ce; ce = &(*ce)->next, no++)
+    {
+        ce_last = ce;
+        if ((*ce)->pos == norm)
+        {
+            ce_this = *ce;
+            *ce = (*ce)->next;   /* remove from list */
+            
+            ce_this->next = b->file[cat].cache_entries;  /* move to front */
+            b->file[cat].cache_entries = ce_this;
+            
+            if (wr)
+            {
+                memcpy (ce_this->buf + off, userbuf, 
+                        b->file[cat].head.block_size);
+                ce_this->dirty = 1;
+            }
+            else
+                memcpy (userbuf, ce_this->buf + off,
+                        b->file[cat].head.block_size);
+            return 1;
+        }
+    }
+    if (no >= 40)
+    {
+        assert (no == 40);
+        assert (ce_last && *ce_last);
+        ce_this = *ce_last;
+        *ce_last = 0;  /* remove the last entry from list */
+        if (ce_this->dirty)
+        {
+            yaz_log (b->log_io, "bf_write: get_block");
+            bf_write (b->file[cat].bf, ce_this->pos, 0, 0, ce_this->buf);
+        }
+        xfree (ce_this->buf);
+        xfree (ce_this);
+    }
+    ce_this = xmalloc (sizeof(*ce_this));
+    ce_this->next = b->file[cat].cache_entries;
+    b->file[cat].cache_entries = ce_this;
+    ce_this->buf = xmalloc (ISAMB_CACHE_ENTRY_SIZE);
+    ce_this->pos = norm;
+    yaz_log (b->log_io, "bf_read: get_block");
+    if (!bf_read (b->file[cat].bf, norm, 0, 0, ce_this->buf))
+        memset (ce_this->buf, 0, ISAMB_CACHE_ENTRY_SIZE);
+    if (wr)
+    {
+        memcpy (ce_this->buf + off, userbuf, b->file[cat].head.block_size);
+        ce_this->dirty = 1;
+    }
+    else
+    {
+        ce_this->dirty = 0;
+        memcpy (userbuf, ce_this->buf + off, b->file[cat].head.block_size);
+    }
+    return 1;
+}
+
+
 void isamb_close (ISAMB isamb)
 {
     int i;
     for (i = 0; i<isamb->no_cat; i++)
     {
+        flush_blocks (isamb, i);
         if (isamb->file[i].head_dirty)
             bf_write (isamb->file[i].bf, 0, 0,
                       sizeof(struct ISAMB_head), &isamb->file[i].head);
+        
+        bf_close (isamb->file[i].bf);
     }
     xfree (isamb->file);
     xfree (isamb->method);
     xfree (isamb);
 }
 
+
 struct ISAMB_block *open_block (ISAMB b, ISAMC_P pos)
 {
     int cat = pos&3;
@@ -115,12 +266,24 @@ struct ISAMB_block *open_block (ISAMB b, ISAMC_P pos)
     p = xmalloc (sizeof(*p));
     p->pos = pos;
     p->cat = pos & 3;
-    p->bytes = xmalloc (b->file[cat].head.block_size);
-    bf_read (b->file[cat].bf, pos/4, 0, 0, p->bytes);
-    p->leaf = p->bytes[0];
-    p->size = p->bytes[1] + 256 * p->bytes[2];
-    p->offset = ISAMB_DATA_OFFSET;
+    p->buf = xmalloc (b->file[cat].head.block_size);
+
+    if (!get_block (b, pos, p->buf, 0))
+    {
+        yaz_log (b->log_io, "bf_read: open_block");
+        if (!bf_read (b->file[cat].bf, pos/4, 0, 0, p->buf))
+        {
+            yaz_log (LOG_FATAL, "read failure for pos=%ld block=%ld",
+                     (long) pos, (long) pos/4);
+            abort();
+        }
+    }
+    p->bytes = p->buf + ISAMB_DATA_OFFSET;
+    p->leaf = p->buf[0];
+    p->size = p->buf[1] + 256 * p->buf[2] - ISAMB_DATA_OFFSET;
+    p->offset = 0;
     p->dirty = 0;
+    p->deleted = 0;
     p->decodeClientData = (*b->method->code_start)(ISAMC_DECODE);
     return p;
 }
@@ -128,159 +291,110 @@ struct ISAMB_block *open_block (ISAMB b, ISAMC_P pos)
 struct ISAMB_block *new_block (ISAMB b, int leaf, int cat)
 {
     struct ISAMB_block *p;
-    int block_no;
-    
+
     p = xmalloc (sizeof(*p));
-    block_no = b->file[cat].head.last_block++;
-    p->cat = cat;
-    p->pos = block_no * 4 + cat;
+    p->buf = xmalloc (b->file[cat].head.block_size);
+
+    if (!b->file[cat].head.free_list)
+    {
+        int block_no;
+        block_no = b->file[cat].head.last_block++;
+        p->pos = block_no * 4 + cat;
+    }
+    else
+    {
+        p->pos = b->file[cat].head.free_list;
+        if (!get_block (b, p->pos, p->buf, 0))
+        {
+            yaz_log (b->log_io, "bf_read: new_block");
+            if (!bf_read (b->file[cat].bf, p->pos/4, 0, 0, p->buf))
+            {
+                yaz_log (LOG_FATAL, "read failure for pos=%ld block=%ld",
+                         (long) p->pos/4, (long) p->pos/4);
+                abort ();
+            }
+        }
+        yaz_log (b->log_freelist, "got block %d from freelist %d:%d", p->pos,
+                 cat, p->pos/4);
+        memcpy (&b->file[cat].head.free_list, p->buf, sizeof(int));
+    }
     p->cat = cat;
     b->file[cat].head_dirty = 1;
-    p->bytes = xmalloc (b->file[cat].head.block_size);
-    memset (p->bytes, 0, b->file[cat].head.block_size);
+    memset (p->buf, 0, b->file[cat].head.block_size);
+    p->bytes = p->buf + ISAMB_DATA_OFFSET;
     p->leaf = leaf;
-    p->size = ISAMB_DATA_OFFSET;
+    p->size = 0;
     p->dirty = 1;
-    p->offset = ISAMB_DATA_OFFSET;
+    p->deleted = 0;
+    p->offset = 0;
     p->decodeClientData = (*b->method->code_start)(ISAMC_DECODE);
     return p;
 }
 
-void close_block (ISAMB b, struct ISAMB_block *p)
+struct ISAMB_block *new_leaf (ISAMB b, int cat)
 {
-    if (!p)
-        return;
-    if (p->dirty)
-    {
-        p->bytes[0] = p->leaf;
-        p->bytes[1] = p->size & 255;
-        p->bytes[2] = p->size >> 8;
-        bf_write (b->file[p->cat].bf, p->pos/4, 0, 0, p->bytes);
-    }
-    (*b->method->code_stop)(ISAMC_DECODE, p->decodeClientData);
-    xfree (p->bytes);
-    xfree (p);
+    return new_block (b, 1, cat);
 }
 
-void insert_sub (ISAMB b, struct ISAMB_block *p, const void *new_item,
-                 struct ISAMB_block **sp,
-                 void *sub_item, int *sub_size);
 
-void insert_leaf (ISAMB b, struct ISAMB_block *p, const void *new_item,
-                  struct ISAMB_block **sp,
-                  void *sub_item, int *sub_size)
+struct ISAMB_block *new_int (ISAMB b, int cat)
 {
-    char dst_buf[DST_BUF_SIZE];
-    char *dst = dst_buf;
-    char *src = p->bytes + ISAMB_DATA_OFFSET;
-    char *endp = p->bytes + p->size;
-    void *c1 = (*b->method->code_start)(ISAMC_DECODE);
-    void *c2 = (*b->method->code_start)(ISAMC_ENCODE);
-    char *half1 = 0;
-    char *half2 = 0;
-    char *cut = dst_buf + p->size / 2;
-    char cut_item_buf[DST_ITEM_MAX];
-    int cut_item_size = 0;
+    return new_block (b, 0, cat);
+}
 
-    while (src != endp)
+void close_block (ISAMB b, struct ISAMB_block *p)
+{
+    if (!p)
+        return;
+    if (p->deleted)
     {
-        char file_item_buf[DST_ITEM_MAX];
-        char *file_item = file_item_buf;
-
-        (*b->method->code_item)(ISAMC_DECODE, c1, &file_item, &src);
-        if (new_item)
+        yaz_log (b->log_freelist, "release block %d from freelist %d:%d",
+                 p->pos, p->cat, p->pos/4);
+        memcpy (p->buf, &b->file[p->cat].head.free_list, sizeof(int));
+        b->file[p->cat].head.free_list = p->pos;
+        if (!get_block (b, p->pos, p->buf, 1))
         {
-            int d = (*b->method->compare_item)(file_item_buf, new_item);
-            if (d > 0)
-            {
-                char *item_ptr = (char*) new_item;
-                (*b->method->code_item)(ISAMC_ENCODE, c2, &dst, &item_ptr);
-                new_item = 0;
-                p->dirty = 1;
-            }
-            else if (d == 0)
-            {
-                new_item = 0;
-            }
-        }
-        
-        if (!half1 && dst > cut)   
-        {
-            half1 = dst; /* candidate for splitting */
-
-            file_item = file_item_buf;
-            (*b->method->code_item)(ISAMC_ENCODE, c2, &dst, &file_item);
-
-            cut_item_size = file_item - file_item_buf;
-            memcpy (cut_item_buf, file_item_buf, cut_item_size);
-
-            half2 = dst;
+            yaz_log (b->log_io, "bf_write: close_block");
+            bf_write (b->file[p->cat].bf, p->pos/4, 0, 0, p->buf);
         }
-        else
-        {
-            file_item = file_item_buf;
-            (*b->method->code_item)(ISAMC_ENCODE, c2, &dst, &file_item);
-        }
-    }
-    if (new_item)
-    {
-        char *item_ptr = (char*) new_item;
-        (*b->method->code_item)(ISAMC_ENCODE, c2, &dst, &item_ptr);
-        new_item = 0;
-        p->dirty = 1;
     }
-    p->size = dst - dst_buf + ISAMB_DATA_OFFSET;
-    if (p->size > b->file[p->cat].head.block_size)
+    else if (p->dirty)
     {
-        char *first_dst;
-        char *cut_item = cut_item_buf;
- 
-       /* first half */
-        p->size = half1 - dst_buf + ISAMB_DATA_OFFSET;
-        memcpy (p->bytes+ISAMB_DATA_OFFSET, dst_buf, half1 - dst_buf);
-
-        /* second half */
-        *sp = new_block (b, 1, p->cat);
-
-        (*b->method->code_reset)(c2);
-
-        first_dst = (*sp)->bytes + ISAMB_DATA_OFFSET;
-
-        (*b->method->code_item)(ISAMC_ENCODE, c2, &first_dst, &cut_item);
-
-        memcpy (first_dst, half2, dst - half2);
-
-        (*sp)->size = (first_dst - (char*) (*sp)->bytes) + (dst - half2);
-        (*sp)->dirty = 1;
-        p->dirty = 1;
-        memcpy (sub_item, cut_item_buf, cut_item_size);
-        *sub_size = cut_item_size;
-
-        yaz_log (LOG_LOG, "l split %d / %d", p->size, (*sp)->size);
-
-    }
-    else
-    {
-        assert (p->size > ISAMB_DATA_OFFSET);
-        assert (p->size <= b->file[p->cat].head.block_size);
-        memcpy (p->bytes+ISAMB_DATA_OFFSET, dst_buf, dst - dst_buf);
-        *sp = 0;
+        int size = p->size + ISAMB_DATA_OFFSET;
+        p->buf[0] = p->leaf;
+        p->buf[1] = size & 255;
+        p->buf[2] = size >> 8;
+        if (!get_block (b, p->pos, p->buf, 1))
+        {
+            yaz_log (b->log_io, "bf_write: close_block");
+            bf_write (b->file[p->cat].bf, p->pos/4, 0, 0, p->buf);
+        }
     }
-    (*b->method->code_stop)(ISAMC_DECODE, c1);
-    (*b->method->code_stop)(ISAMC_ENCODE, c2);
+    (*b->method->code_stop)(ISAMC_DECODE, p->decodeClientData);
+    xfree (p->buf);
+    xfree (p);
 }
 
-void insert_int (ISAMB b, struct ISAMB_block *p, const void *new_item,
-                 struct ISAMB_block **sp,
-                 void *split_item, int *split_size)
+int insert_sub (ISAMB b, struct ISAMB_block **p,
+                void *new_item, int *mode,
+                ISAMC_I stream,
+                struct ISAMB_block **sp,
+                void *sub_item, int *sub_size,
+                void *max_item);
+
+int insert_int (ISAMB b, struct ISAMB_block *p, void *lookahead_item,
+                int *mode,
+                ISAMC_I stream, struct ISAMB_block **sp,
+                void *split_item, int *split_size, void *last_max_item)
 {
-    char *startp = p->bytes + ISAMB_DATA_OFFSET;
+    char *startp = p->bytes;
     char *src = startp;
     char *endp = p->bytes + p->size;
     int pos;
     struct ISAMB_block *sub_p1 = 0, *sub_p2 = 0;
     char sub_item[DST_ITEM_MAX];
     int sub_size;
+    int more;
 
     *sp = 0;
 
@@ -290,13 +404,14 @@ void insert_int (ISAMB b, struct ISAMB_block *p, const void *new_item,
         int item_len;
         int d;
         decode_ptr (&src, &item_len);
-        d = (*b->method->compare_item)(src, new_item);
+        d = (*b->method->compare_item)(src, lookahead_item);
         if (d > 0)
         {
             sub_p1 = open_block (b, pos);
             assert (sub_p1);
-            insert_sub (b, sub_p1, new_item, &sub_p2, 
-                        sub_item, &sub_size);
+            more = insert_sub (b, &sub_p1, lookahead_item, mode,
+                               stream, &sub_p2, 
+                               sub_item, &sub_size, src);
             break;
         }
         src += item_len;
@@ -306,15 +421,16 @@ void insert_int (ISAMB b, struct ISAMB_block *p, const void *new_item,
     {
         sub_p1 = open_block (b, pos);
         assert (sub_p1);
-        insert_sub (b, sub_p1, new_item, &sub_p2, 
-                    sub_item, &sub_size);
+        more = insert_sub (b, &sub_p1, lookahead_item, mode, stream, &sub_p2, 
+                           sub_item, &sub_size, last_max_item);
     }
     if (sub_p2)
     {
+        /* there was a split - must insert pointer in this one */
         char dst_buf[DST_BUF_SIZE];
         char *dst = dst_buf;
 
-        assert (sub_size < 20);
+        assert (sub_size < 30 && sub_size > 1);
 
         memcpy (dst, startp, src - startp);
                 
@@ -331,8 +447,8 @@ void insert_int (ISAMB b, struct ISAMB_block *p, const void *new_item,
             memcpy (dst, src, endp - src);
             dst += endp - src;
         }
-        p->size = dst - dst_buf + ISAMB_DATA_OFFSET;
-        if (p->size <= b->file[p->cat].head.block_size)
+        p->size = dst - dst_buf;
+        if (p->size <= b->file[p->cat].head.block_max)
         {
             memcpy (startp, dst_buf, dst - dst_buf);
         }
@@ -352,93 +468,192 @@ void insert_int (ISAMB b, struct ISAMB_block *p, const void *new_item,
                 decode_ptr (&src, &pos);
             }
             p_new_size = src - dst_buf;
-            memcpy (p->bytes + ISAMB_DATA_OFFSET, dst_buf, p_new_size);
-            p_new_size += ISAMB_DATA_OFFSET;
+            memcpy (p->bytes, dst_buf, p_new_size);
 
             decode_ptr (&src, split_size);
             memcpy (split_item, src, *split_size);
             src += *split_size;
 
-            *sp = new_block (b, 0, p->cat);
+            *sp = new_int (b, p->cat);
             (*sp)->size = endp - src;
-            memcpy ((*sp)->bytes+ISAMB_DATA_OFFSET, src, (*sp)->size);
-            (*sp)->size += ISAMB_DATA_OFFSET;
+            memcpy ((*sp)->bytes, src, (*sp)->size);
 
-            yaz_log (LOG_LOG, "i split %d -> %d %d",
-                     p->size, p_new_size, (*sp)->size);
             p->size = p_new_size;
         }
         p->dirty = 1;
         close_block (b, sub_p2);
     }
     close_block (b, sub_p1);
+    return more;
 }
 
-void insert_sub (ISAMB b, struct ISAMB_block *p, const void *new_item,
-                struct ISAMB_block **sp,
-                void *sub_item, int *sub_size)
-{
-    if (p->leaf)
-        insert_leaf (b, p, new_item, sp, sub_item, sub_size);
-    else
-        insert_int (b, p, new_item, sp, sub_item, sub_size);
-}
 
-int insert_flat (ISAMB b, const void *new_item, ISAMC_P *posp)
+int insert_leaf (ISAMB b, struct ISAMB_block **sp1, void *lookahead_item,
+                 int *lookahead_mode, ISAMC_I stream, struct ISAMB_block **sp2,
+                 void *sub_item, int *sub_size,
+                 void *max_item)
 {
-    struct ISAMB_block *p = 0;
+    struct ISAMB_block *p = *sp1;
     char *src = 0, *endp = 0;
     char dst_buf[DST_BUF_SIZE], *dst = dst_buf;
     int new_size;
-    ISAMB_P pos = *posp;
     void *c1 = (*b->method->code_start)(ISAMC_DECODE);
     void *c2 = (*b->method->code_start)(ISAMC_ENCODE);
-    
-    if (pos)
-    {
-        p = open_block (b, pos);
-        if (!p)
-            return -1;
-        src = p->bytes + ISAMB_DATA_OFFSET;
-        endp = p->bytes + p->size;
+    int more = 1;
+    int quater = b->file[b->no_cat-1].head.block_max / 4;
+    char *cut = dst_buf + quater * 2;
+    char *maxp = dst_buf + b->file[b->no_cat-1].head.block_max;
+    char *half1 = 0;
+    char *half2 = 0;
+    char cut_item_buf[DST_ITEM_MAX];
+    int cut_item_size = 0;
 
-    }
-    while (p && src != endp)
+    if (p && p->size)
     {
         char file_item_buf[DST_ITEM_MAX];
         char *file_item = file_item_buf;
-
+            
+        src = p->bytes;
+        endp = p->bytes + p->size;
         (*b->method->code_item)(ISAMC_DECODE, c1, &file_item, &src);
-        if (new_item)
+        while (1)
         {
-            int d = (*b->method->compare_item)(file_item_buf, new_item);
+            char *dst_item = 0;
+            char *dst_0 = dst;
+            char *lookahead_next;
+            int d = -1;
+            
+            if (lookahead_item)
+                d = (*b->method->compare_item)(file_item_buf, lookahead_item);
+            
             if (d > 0)
             {
-                char *item_ptr = (char*) new_item;
-                (*b->method->code_item)(ISAMC_ENCODE, c2, &dst, &item_ptr);
-                new_item = 0;
+                dst_item = lookahead_item;
+                assert (*lookahead_mode);
+            }
+            else
+                dst_item = file_item_buf;
+            if (!*lookahead_mode && d == 0)
+            {
                 p->dirty = 1;
             }
+            else if (!half1 && dst > cut)
+            {
+                char *dst_item_0 = dst_item;
+                half1 = dst; /* candidate for splitting */
+                
+                (*b->method->code_item)(ISAMC_ENCODE, c2, &dst, &dst_item);
+                
+                cut_item_size = dst_item - dst_item_0;
+                memcpy (cut_item_buf, dst_item_0, cut_item_size);
+                
+                half2 = dst;
+            }
+            else
+                (*b->method->code_item)(ISAMC_ENCODE, c2, &dst, &dst_item);
+            if (d > 0)  
+            {
+                if (dst > maxp)
+                {
+                    dst = dst_0;
+                    lookahead_item = 0;
+                }
+                else
+                {
+                    lookahead_next = lookahead_item;
+                    if (!(*stream->read_item)(stream->clientData,
+                                              &lookahead_next,
+                                              lookahead_mode))
+                    {
+                        lookahead_item = 0;
+                        more = 0;
+                    }
+                    if (lookahead_item && max_item &&
+                        (*b->method->compare_item)(max_item, lookahead_item) <= 0)
+                    {
+                        /* max_item 1 */
+                        lookahead_item = 0;
+                    }
+                    
+                    p->dirty = 1;
+                }
+            }
             else if (d == 0)
             {
-                new_item = 0;
+                lookahead_next = lookahead_item;
+                if (!(*stream->read_item)(stream->clientData,
+                                          &lookahead_next, lookahead_mode))
+                {
+                    lookahead_item = 0;
+                    more = 0;
+                }
+                if (src == endp)
+                    break;
+                file_item = file_item_buf;
+                (*b->method->code_item)(ISAMC_DECODE, c1, &file_item, &src);
+            }
+            else
+            {
+                if (src == endp)
+                    break;
+                file_item = file_item_buf;
+                (*b->method->code_item)(ISAMC_DECODE, c1, &file_item, &src);
             }
         }
-        file_item = file_item_buf;
-        (*b->method->code_item)(ISAMC_ENCODE, c2, &dst, &file_item);
     }
-    if (new_item)
+    maxp = dst_buf + b->file[b->no_cat-1].head.block_max + quater;
+    while (lookahead_item)
     {
-        char *item_ptr = (char*) new_item;
-        (*b->method->code_item)(ISAMC_ENCODE, c2, &dst, &item_ptr);
-        new_item = 0;
+        char *dst_item = lookahead_item;
+        char *dst_0 = dst;
+        
+        if (max_item &&
+            (*b->method->compare_item)(max_item, lookahead_item) <= 0)
+        {
+            /* max_item 2 */
+            break;
+        }
+        if (!*lookahead_mode)
+        {
+            yaz_log (LOG_WARN, "Inconsistent register (2)");
+            abort();
+        }
+        else if (!half1 && dst > cut)   
+        {
+            char *dst_item_0 = dst_item;
+            half1 = dst; /* candidate for splitting */
+            
+            (*b->method->code_item)(ISAMC_ENCODE, c2, &dst, &dst_item);
+            
+            cut_item_size = dst_item - dst_item_0;
+            memcpy (cut_item_buf, dst_item_0, cut_item_size);
+            
+            half2 = dst;
+        }
+        else
+            (*b->method->code_item)(ISAMC_ENCODE, c2, &dst, &dst_item);
+
+        if (dst > maxp)
+        {
+            dst = dst_0;
+            break;
+        }
         if (p)
             p->dirty = 1;
+        dst_item = lookahead_item;
+        if (!(*stream->read_item)(stream->clientData, &dst_item,
+                                  lookahead_mode))
+        {
+            lookahead_item = 0;
+            more = 0;
+        }
     }
-    new_size = dst - dst_buf + ISAMB_DATA_OFFSET;
-    if (p && new_size > p->size)
+    new_size = dst - dst_buf;
+    if (p && p->cat != b->no_cat-1 && 
+        new_size > b->file[p->cat].head.block_max)
     {
-        yaz_log (LOG_LOG, "resize %d -> %d", p->size, new_size);
+        /* non-btree block will be removed */
+        p->deleted = 1;
         close_block (b, p);
         /* delete it too!! */
         p = 0; /* make a new one anyway */
@@ -447,39 +662,100 @@ int insert_flat (ISAMB b, const void *new_item, ISAMC_P *posp)
     {   /* must create a new one */
         int i;
         for (i = 0; i < b->no_cat; i++)
-            if (new_size <= b->file[i].head.block_size)
+            if (new_size <= b->file[i].head.block_max)
                 break;
-        p = new_block (b, 1, i);
+        if (i == b->no_cat)
+            i = b->no_cat - 1;
+        p = new_leaf (b, i);
+    }
+    if (new_size > b->file[p->cat].head.block_max)
+    {
+        char *first_dst;
+        char *cut_item = cut_item_buf;
+
+        assert (half1);
+        assert (half2);
+
+       /* first half */
+        p->size = half1 - dst_buf;
+        memcpy (p->bytes, dst_buf, half1 - dst_buf);
+
+        /* second half */
+        *sp2 = new_leaf (b, p->cat);
+
+        (*b->method->code_reset)(c2);
+
+        first_dst = (*sp2)->bytes;
+
+        (*b->method->code_item)(ISAMC_ENCODE, c2, &first_dst, &cut_item);
+
+        memcpy (first_dst, half2, dst - half2);
+
+        (*sp2)->size = (first_dst - (*sp2)->bytes) + (dst - half2);
+        (*sp2)->dirty = 1;
+        p->dirty = 1;
+        memcpy (sub_item, cut_item_buf, cut_item_size);
+        *sub_size = cut_item_size;
+    }
+    else
+    {
+        memcpy (p->bytes, dst_buf, dst - dst_buf);
+        p->size = new_size;
     }
-    memcpy (p->bytes+ISAMB_DATA_OFFSET, dst_buf, dst - dst_buf);
-    p->size = new_size;
-    *posp = p->pos;
     (*b->method->code_stop)(ISAMC_DECODE, c1);
     (*b->method->code_stop)(ISAMC_ENCODE, c2);
-    close_block (b, p);
-    return 0;
+    *sp1 = p;
+    return more;
+}
+
+int insert_sub (ISAMB b, struct ISAMB_block **p, void *new_item,
+                int *mode,
+                ISAMC_I stream,
+                struct ISAMB_block **sp,
+                void *sub_item, int *sub_size,
+                void *max_item)
+{
+    if (!*p || (*p)->leaf)
+        return insert_leaf (b, p, new_item, mode, stream, sp, sub_item, 
+                            sub_size, max_item);
+    else
+        return insert_int (b, *p, new_item, mode, stream, sp, sub_item,
+                           sub_size, max_item);
 }
 
-int isamb_insert_one (ISAMB b, const void *item, ISAMC_P pos)
+int isamb_merge (ISAMB b, ISAMC_P pos, ISAMC_I stream)
 {
+    char item_buf[DST_ITEM_MAX];
+    char *item_ptr;
+    int i_mode;
+    int more;
 
-    if ((pos & 3) != b->no_cat-1)
+    if (b->cache < 0)
     {
-        /* note if pos == 0 we go here too! */
-        /* flat insert */
-        insert_flat (b, item, &pos);
+        int more = 1;
+        while (more)
+        {
+            item_ptr = item_buf;
+            more =
+                (*stream->read_item)(stream->clientData, &item_ptr, &i_mode);
+        }
+        return 1;
     }
-    else
+    item_ptr = item_buf;
+    more = (*stream->read_item)(stream->clientData, &item_ptr, &i_mode);
+    while (more)
     {
-        /* b-tree insert */
-        struct ISAMB_block *p, *sp = 0;
+        struct ISAMB_block *p = 0, *sp = 0;
         char sub_item[DST_ITEM_MAX];
         int sub_size;
-
-        insert_sub (b, p, item, &sp, sub_item, &sub_size);
+        
+        if (pos)
+            p = open_block (b, pos);
+        more = insert_sub (b, &p, item_buf, &i_mode, stream, &sp,
+                            sub_item, &sub_size, 0);
         if (sp)
         {    /* increase level of tree by one */
-            struct ISAMB_block *p2 = new_block (b, 0, p->cat);
+            struct ISAMB_block *p2 = new_int (b, p->cat);
             char *dst = p2->bytes + p2->size;
             
             encode_ptr (&dst, p->pos);
@@ -489,7 +765,7 @@ int isamb_insert_one (ISAMB b, const void *item, ISAMC_P pos)
             dst += sub_size;
             encode_ptr (&dst, sp->pos);
             
-            p2->size = dst - (char*) p2->bytes;
+            p2->size = dst - p2->bytes;
             pos = p2->pos;  /* return new super page */
             close_block (b, sp);
             close_block (b, p2);
@@ -501,55 +777,71 @@ int isamb_insert_one (ISAMB b, const void *item, ISAMC_P pos)
     return pos;
 }
 
-ISAMB_P isamb_merge (ISAMB b, ISAMB_P pos, ISAMC_I data)
-{
-    int i_mode;
-    char item_buf[DST_ITEM_MAX];
-    char *item_ptr = item_buf;
-    while ((*data->read_item)(data->clientData, &item_ptr, &i_mode))
-    {
-        item_ptr = item_buf;
-        pos = isamb_insert_one (b, item_buf, pos);
-    }
-    return pos;
-}
-
-ISAMB_PP isamb_pp_open (ISAMB isamb, ISAMB_P pos)
+ISAMB_PP isamb_pp_open_x (ISAMB isamb, ISAMB_P pos, int *level)
 {
     ISAMB_PP pp = xmalloc (sizeof(*pp));
 
     pp->isamb = isamb;
     pp->block = xmalloc (10 * sizeof(*pp->block));
 
+    pp->pos = pos;
     pp->level = 0;
+    pp->total_size = 0;
+    pp->no_blocks = 0;
     while (1)
     {
         struct ISAMB_block *p = open_block (isamb, pos);
         char *src = p->bytes + p->offset;
         pp->block[pp->level] = p;
 
-        if (p->bytes[0]) /* leaf */
+        pp->total_size += p->size;
+        pp->no_blocks++;
+
+        if (p->leaf)
             break;
 
         decode_ptr (&src, &pos);
-        p->offset = src - (char*) p->bytes;
+        p->offset = src - p->bytes;
         pp->level++;
     }
     pp->block[pp->level+1] = 0;
+    if (level)
+        *level = pp->level;
     return pp;
 }
 
-void isamb_pp_close (ISAMB_PP pp)
+ISAMB_PP isamb_pp_open (ISAMB isamb, ISAMB_P pos)
+{
+    return isamb_pp_open_x (isamb, pos, 0);
+}
+
+void isamb_pp_close_x (ISAMB_PP pp, int *size, int *blocks)
 {
     int i;
     if (!pp)
         return;
+    if (size)
+        *size = pp->total_size;
+    if (blocks)
+        *blocks = pp->no_blocks;
     for (i = 0; i <= pp->level; i++)
         close_block (pp->isamb, pp->block[i]);
     xfree (pp->block);
     xfree (pp);
 }
 
+int isamb_block_info (ISAMB isamb, int cat)
+{
+    if (cat >= 0 && cat < isamb->no_cat)
+        return isamb->file[cat].head.block_size;
+    return -1;
+}
+
+void isamb_pp_close (ISAMB_PP pp)
+{
+    isamb_pp_close_x (pp, 0, 0);
+}
+
 int isamb_pp_read (ISAMB_PP pp, void *buf)
 {
     char *dst = buf;
@@ -569,7 +861,7 @@ int isamb_pp_read (ISAMB_PP pp, void *buf)
             pp->block[pp->level] = 0;
             (pp->level)--;
             p = pp->block[pp->level];
-            assert (p->bytes[0] == 0);  /* must be int */
+            assert (!p->leaf);  /* must be int */
         }
         src = p->bytes + p->offset;
         
@@ -584,8 +876,11 @@ int isamb_pp_read (ISAMB_PP pp, void *buf)
         while (1)
         {
             pp->block[pp->level] = p = open_block (pp->isamb, pos);
+
+            pp->total_size += p->size;
+            pp->no_blocks++;
             
-            if (p->bytes[0]) /* leaf */
+            if (p->leaf) /* leaf */
             {
                 break;
             }
@@ -596,7 +891,7 @@ int isamb_pp_read (ISAMB_PP pp, void *buf)
         }
     }
     assert (p->offset < p->size);
-    assert (p->bytes[0]);
+    assert (p->leaf);
     src = p->bytes + p->offset;
     (*pp->isamb->method->code_item)(ISAMC_DECODE, p->decodeClientData,
                                     &dst, &src);