ADDED   test/kvtest.c
Index: test/kvtest.c
==================================================================
--- /dev/null
+++ test/kvtest.c
@@ -0,0 +1,568 @@
+/*
+** 2016-12-28
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+**
+** This file implements "key-value" performance test for SQLite.  The
+** purpose is to compare the speed of SQLite for accessing large BLOBs
+** versus reading those same BLOB values out of individual files in the
+** filesystem.
+**
+** Run "kvtest" with no arguments for on-line help, or see comments below.
+**
+** HOW TO COMPILE:
+**
+** (1) Gather this source file and a recent SQLite3 amalgamation with its
+**     header into the working directory.  You should have:
+**
+**          kvtest.c       >--- this file
+**          sqlite3.c      \___ SQLite
+**          sqlite3.h      /    amlagamation & header
+**
+** (2) Run you compiler against the two C source code files.
+**
+**    (a) On linux or mac:
+**
+**        OPTS="-DSQLITE_THREADSAFE=0 -DSQLITE_OMIT_LOAD_EXTENSION"
+**        gcc -Os -I. $OPTS kvtest.c sqlite3.c -o kvtest
+**
+**             The $OPTS options can be omitted.  The $OPTS merely omit
+**             the need to link against -ldl and -lpthread, or whatever
+**             the equivalent libraries are called on your system.
+**
+**    (b) Windows with MSVC:
+**
+**        cl -I. kvtest.c sqlite3.c
+**
+** USAGE:
+**
+** (1) Create a test database by running "kvtest init" with appropriate
+**     options.  See the help message for available options.
+**
+** (2) Construct the corresponding pile-of-files database on disk using
+**     the "kvtest export" command.
+**
+** (3) Run tests using "kvtest run" against either the SQLite database or
+**     the pile-of-files database and with appropriate options.
+**
+** For example:
+**
+**       ./kvtest init x1.db --count 100000 --size 10000
+**       mkdir x1
+**       ./kvtest export x1.db x1
+**       ./kvtest run x1.db --count 10000 --max-id 1000000
+**       ./kvtest run x1 --count 10000 --max-id 1000000
+*/
+static const char zHelp[] = 
+"Usage: kvhelp COMMAND ARGS...\n"
+"\n"
+"   kvhelp init DBFILE --count N --size M --pagesize X\n"
+"\n"
+"        Generate a new test database file named DBFILE containing N\n"
+"        BLOBs each of size M bytes.  The page size of the new database\n"
+"        file will be X\n"
+"\n"
+"   kvhelp export DBFILE DIRECTORY\n"
+"\n"
+"        Export all the blobs in the kv table of DBFILE into separate\n"
+"        files in DIRECTORY.\n"
+"\n"
+"   kvhelp run DBFILE [options]\n"
+"\n"
+"        Run a performance test.  DBFILE can be either the name of a\n"
+"        database or a directory containing sample files.  Options:\n"
+"\n"
+"             --asc                Read blobs in ascending order\n"
+"             --blob-api           Use the BLOB API\n"
+"             --cache-size N       Database cache size\n"
+"             --count N            Read N blobs\n"
+"             --desc               Read blobs in descending order\n"
+"             --max-id N           Maximum blob key to use\n"
+"             --random             Read blobs in a random order\n"
+"             --start N            Start reading with this blob key\n"
+;
+
+/* Reference resources used */
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <assert.h>
+#include <string.h>
+#include "sqlite3.h"
+
+#ifndef _WIN32
+# include <unistd.h>
+#else
+  /* Provide Windows equivalent for the needed parts of unistd.h */
+# include <io.h>
+# define R_OK 2
+# define S_ISDIR(m) (((m) & S_IFMT) == S_IFDIR)
+# define access _access
+#endif
+
+
+/*
+** Show thqe help text and quit.
+*/
+static void showHelp(void){
+  fprintf(stdout, "%s", zHelp);
+  exit(1);
+}
+
+/*
+** Show an error message an quit.
+*/
+static void fatalError(const char *zFormat, ...){
+  va_list ap;
+  fprintf(stdout, "ERROR: ");
+  va_start(ap, zFormat);
+  vfprintf(stdout, zFormat, ap);
+  va_end(ap);
+  fprintf(stdout, "\n");
+  exit(1);
+}
+
+/*
+** Check the filesystem object zPath.  Determine what it is:
+**
+**    PATH_DIR     A directory
+**    PATH_DB      An SQLite database
+**    PATH_NEXIST  Does not exist
+**    PATH_OTHER   Something else
+*/
+#define PATH_DIR     1
+#define PATH_DB      2
+#define PATH_NEXIST  0
+#define PATH_OTHER   99
+static int pathType(const char *zPath){
+  struct stat x;
+  int rc;
+  if( access(zPath,R_OK) ) return PATH_NEXIST;
+  memset(&x, 0, sizeof(x));
+  rc = stat(zPath, &x);
+  if( rc<0 ) return PATH_OTHER;
+  if( S_ISDIR(x.st_mode) ) return PATH_DIR;
+  if( (x.st_size%512)==0 ) return PATH_DB;
+  return PATH_OTHER;
+}
+
+/*
+** A Pseudo-random number generator with a fixed seed.  Use this so
+** that the same sequence of "random" numbers are generated on each
+** run, for repeatability.
+*/
+static unsigned int randInt(void){
+  static unsigned int x = 0x333a13cd;
+  static unsigned int y = 0xecb2adea;
+  x = (x>>1) ^ ((1+~(x&1)) & 0xd0000001);
+  y = y*1103515245 + 12345;
+  return x^y;
+}
+
+/*
+** Do database initialization.
+*/
+static int initMain(int argc, char **argv){
+  char *zDb;
+  int i, rc;
+  int nCount = 1000;
+  int sz = 10000;
+  int pgsz = 4096;
+  sqlite3 *db;
+  char *zSql;
+  char *zErrMsg = 0;
+
+  assert( strcmp(argv[1],"init")==0 );
+  assert( argc>=3 );
+  zDb = argv[2];
+  for(i=3; i<argc; i++){
+    char *z = argv[i];
+    if( z[0]!='-' ) fatalError("unknown argument: \"%s\"", z);
+    if( z[1]=='-' ) z++;
+    if( strcmp(z, "-count")==0 ){
+      if( i==argc-1 ) fatalError("missing argument on \"%s\"", argv[i]);
+      nCount = atoi(argv[++i]);
+      if( nCount<1 ) fatalError("the --count must be positive");
+      continue;
+    }
+    if( strcmp(z, "-size")==0 ){
+      if( i==argc-1 ) fatalError("missing argument on \"%s\"", argv[i]);
+      sz = atoi(argv[++i]);
+      if( sz<1 ) fatalError("the --size must be positive");
+      continue;
+    }
+    if( strcmp(z, "-pagesize")==0 ){
+      if( i==argc-1 ) fatalError("missing argument on \"%s\"", argv[i]);
+      pgsz = atoi(argv[++i]);
+      if( pgsz<512 || pgsz>65536 || ((pgsz-1)&pgsz)!=0 ){
+        fatalError("the --pagesize must be power of 2 between 512 and 65536");
+      }
+      continue;
+    }
+    fatalError("unknown option: \"%s\"", argv[i]);
+  }
+  rc = sqlite3_open(zDb, &db);
+  if( rc ){
+    fatalError("cannot open database \"%s\": %s", zDb, sqlite3_errmsg(db));
+  }
+  zSql = sqlite3_mprintf(
+    "DROP TABLE IF EXISTS kv;\n"
+    "PRAGMA page_size=%d;\n"
+    "VACUUM;\n"
+    "BEGIN;\n"
+    "CREATE TABLE kv(k INTEGER PRIMARY KEY, v BLOB);\n"
+    "WITH RECURSIVE c(x) AS (VALUES(1) UNION ALL SELECT x+1 FROM c WHERE x<%d)"
+    " INSERT INTO kv(k,v) SELECT x, randomblob(%d) FROM c;\n"
+    "COMMIT;\n",
+    pgsz, nCount, sz
+  );
+  rc = sqlite3_exec(db, zSql, 0, 0, &zErrMsg);
+  if( rc ) fatalError("database create failed: %s", zErrMsg);
+  sqlite3_free(zSql);
+  sqlite3_close(db);
+  return 0;
+}
+
+/*
+** Implementation of the "writefile(X,Y)" SQL function.  The argument Y
+** is written into file X.  The number of bytes written is returned.  Or
+** NULL is returned if something goes wrong, such as being unable to open
+** file X for writing.
+*/
+static void writefileFunc(
+  sqlite3_context *context,
+  int argc,
+  sqlite3_value **argv
+){
+  FILE *out;
+  const char *z;
+  sqlite3_int64 rc;
+  const char *zFile;
+
+  zFile = (const char*)sqlite3_value_text(argv[0]);
+  if( zFile==0 ) return;
+  out = fopen(zFile, "wb");
+  if( out==0 ) return;
+  z = (const char*)sqlite3_value_blob(argv[1]);
+  if( z==0 ){
+    rc = 0;
+  }else{
+    rc = fwrite(z, 1, sqlite3_value_bytes(argv[1]), out);
+  }
+  fclose(out);
+  printf("\r%s   ", zFile); fflush(stdout);
+  sqlite3_result_int64(context, rc);
+}
+
+/*
+** Export the kv table to individual files in the filesystem
+*/
+static int exportMain(int argc, char **argv){
+  char *zDb;
+  char *zDir;
+  sqlite3 *db;
+  char *zSql;
+  int rc;
+  char *zErrMsg = 0;
+
+  assert( strcmp(argv[1],"export")==0 );
+  assert( argc>=3 );
+  zDb = argv[2];
+  if( argc!=4 ) fatalError("Usage: kvtest export DATABASE DIRECTORY");
+  zDir = argv[3];
+  if( pathType(zDir)!=PATH_DIR ){
+    fatalError("object \"%s\" is not a directory", zDir);
+  }
+  rc = sqlite3_open(zDb, &db);
+  if( rc ){
+    fatalError("cannot open database \"%s\": %s", zDb, sqlite3_errmsg(db));
+  }
+  sqlite3_create_function(db, "writefile", 2, SQLITE_UTF8, 0,
+                          writefileFunc, 0, 0);
+  zSql = sqlite3_mprintf(
+    "SELECT writefile(printf('%s/%%06d',k),v) FROM kv;",
+    zDir
+  );
+  rc = sqlite3_exec(db, zSql, 0, 0, &zErrMsg);
+  if( rc ) fatalError("database create failed: %s", zErrMsg);
+  sqlite3_free(zSql);
+  sqlite3_close(db);
+  printf("\n");
+  return 0;
+}
+
+/*
+** Read the content of file zName into memory obtained from sqlite3_malloc64()
+** and return a pointer to the buffer. The caller is responsible for freeing 
+** the memory. 
+**
+** If parameter pnByte is not NULL, (*pnByte) is set to the number of bytes
+** read.
+**
+** For convenience, a nul-terminator byte is always appended to the data read
+** from the file before the buffer is returned. This byte is not included in
+** the final value of (*pnByte), if applicable.
+**
+** NULL is returned if any error is encountered. The final value of *pnByte
+** is undefined in this case.
+*/
+static unsigned char *readFile(const char *zName, int *pnByte){
+  FILE *in = fopen(zName, "rb");
+  long nIn;
+  size_t nRead;
+  unsigned char *pBuf;
+  if( in==0 ) return 0;
+  fseek(in, 0, SEEK_END);
+  nIn = ftell(in);
+  rewind(in);
+  pBuf = sqlite3_malloc64( nIn+1 );
+  if( pBuf==0 ) return 0;
+  nRead = fread(pBuf, nIn, 1, in);
+  fclose(in);
+  if( nRead!=1 ){
+    sqlite3_free(pBuf);
+    return 0;
+  }
+  pBuf[nIn] = 0;
+  if( pnByte ) *pnByte = nIn;
+  return pBuf;
+}
+
+/*
+** Return the current time in milliseconds since the beginning of
+** the Julian epoch.
+*/
+static sqlite3_int64 timeOfDay(void){
+  static sqlite3_vfs *clockVfs = 0;
+  sqlite3_int64 t;
+  if( clockVfs==0 ) clockVfs = sqlite3_vfs_find(0);
+  if( clockVfs->iVersion>=2 && clockVfs->xCurrentTimeInt64!=0 ){
+    clockVfs->xCurrentTimeInt64(clockVfs, &t);
+  }else{
+    double r;
+    clockVfs->xCurrentTime(clockVfs, &r);
+    t = (sqlite3_int64)(r*86400000.0);
+  }
+  return t;
+}
+
+/* Blob access order */
+#define ORDER_ASC     1
+#define ORDER_DESC    2
+#define ORDER_RANDOM  3
+
+/*
+** Run a performance test
+*/
+static int runMain(int argc, char **argv){
+  int eType;                  /* Is zDb a database or a directory? */
+  char *zDb;                  /* Database or directory name */
+  int i;                      /* Loop counter */
+  int rc;                     /* Return code from SQLite calls */
+  int nCount = 1000;          /* Number of blob fetch operations */
+  int nExtra = 0;             /* Extra cycles */
+  int iKey = 1;               /* Next blob key */
+  int iMax = 1000;            /* Largest allowed key */
+  int iPagesize = 0;          /* Database page size */
+  int iCache = 1000;          /* Database cache size in kibibytes */
+  int bBlobApi = 0;           /* Use the incremental blob I/O API */
+  int eOrder = ORDER_ASC;     /* Access order */
+  sqlite3 *db = 0;            /* Database connection */
+  sqlite3_stmt *pStmt = 0;    /* Prepared statement for SQL access */
+  sqlite3_blob *pBlob = 0;    /* Handle for incremental Blob I/O */
+  sqlite3_int64 tmStart;      /* Start time */
+  sqlite3_int64 tmElapsed;    /* Elapsed time */
+  int nData = 0;              /* Bytes of data */
+  sqlite3_int64 nTotal = 0;   /* Total data read */
+  unsigned char *pData;       /* Content of the blob */
+  
+
+  assert( strcmp(argv[1],"run")==0 );
+  assert( argc>=3 );
+  zDb = argv[2];
+  eType = pathType(zDb);
+  if( eType==PATH_OTHER ) fatalError("unknown object type: \"%s\"", zDb);
+  if( eType==PATH_NEXIST ) fatalError("object does not exist: \"%s\"", zDb);
+  for(i=3; i<argc; i++){
+    char *z = argv[i];
+    if( z[0]!='-' ) fatalError("unknown argument: \"%s\"", z);
+    if( z[1]=='-' ) z++;
+    if( strcmp(z, "-count")==0 ){
+      if( i==argc-1 ) fatalError("missing argument on \"%s\"", argv[i]);
+      nCount = atoi(argv[++i]);
+      if( nCount<1 ) fatalError("the --count must be positive");
+      continue;
+    }
+    if( strcmp(z, "-max-id")==0 ){
+      if( i==argc-1 ) fatalError("missing argument on \"%s\"", argv[i]);
+      iMax = atoi(argv[++i]);
+      if( iMax<1 ) fatalError("the --max-id must be positive");
+      continue;
+    }
+    if( strcmp(z, "-start")==0 ){
+      if( i==argc-1 ) fatalError("missing argument on \"%s\"", argv[i]);
+      iKey = atoi(argv[++i]);
+      if( iKey<1 ) fatalError("the --start must be positive");
+      continue;
+    }
+    if( strcmp(z, "-cache-size")==0 ){
+      if( i==argc-1 ) fatalError("missing argument on \"%s\"", argv[i]);
+      iCache = atoi(argv[++i]);
+      continue;
+    }
+    if( strcmp(z, "-random")==0 ){
+      eOrder = ORDER_RANDOM;
+      continue;
+    }
+    if( strcmp(z, "-asc")==0 ){
+      eOrder = ORDER_ASC;
+      continue;
+    }
+    if( strcmp(z, "-desc")==0 ){
+      eOrder = ORDER_DESC;
+      continue;
+    }
+    if( strcmp(z, "-blob-api")==0 ){
+      bBlobApi = 1;
+      continue;
+    }
+    fatalError("unknown option: \"%s\"", argv[i]);
+  }
+  tmStart = timeOfDay();
+  if( eType==PATH_DB ){
+    char *zSql;
+    rc = sqlite3_open(zDb, &db);
+    if( rc ){
+      fatalError("cannot open database \"%s\": %s", zDb, sqlite3_errmsg(db));
+    }
+    zSql = sqlite3_mprintf("PRAGMA cache_size=%d", iCache);
+    sqlite3_exec(db, zSql, 0, 0, 0);
+    sqlite3_free(zSql);
+    pStmt = 0;
+    sqlite3_prepare_v2(db, "PRAGMA page_size", -1, &pStmt, 0);
+    if( sqlite3_step(pStmt)==SQLITE_ROW ){
+      iPagesize = sqlite3_column_int(pStmt, 0);
+    }
+    sqlite3_finalize(pStmt);
+    sqlite3_prepare_v2(db, "PRAGMA cache_size", -1, &pStmt, 0);
+    if( sqlite3_step(pStmt)==SQLITE_ROW ){
+      iCache = sqlite3_column_int(pStmt, 0);
+    }else{
+      iCache = 0;
+    }
+    sqlite3_finalize(pStmt);
+    pStmt = 0;
+    sqlite3_exec(db, "BEGIN", 0, 0, 0);
+  }
+  for(i=0; i<nCount; i++){
+    if( eType==PATH_DIR ){
+      /* CASE 1: Reading blobs out of separate files */
+      char *zKey;
+      zKey = sqlite3_mprintf("%s/%06d", zDb, iKey);
+      nData = 0;
+      pData = readFile(zKey, &nData);
+      sqlite3_free(zKey);
+      sqlite3_free(pData);
+    }else if( bBlobApi ){
+      /* CASE 2: Reading from database using the incremental BLOB I/O API */
+      if( pBlob==0 ){
+        rc = sqlite3_blob_open(db, "main", "kv", "v", iKey, 0, &pBlob);
+        if( rc ){
+          fatalError("could not open sqlite3_blob handle: %s",
+                     sqlite3_errmsg(db));
+        }
+      }else{
+        rc = sqlite3_blob_reopen(pBlob, iKey);
+      }
+      if( rc==SQLITE_OK ){
+        nData = sqlite3_blob_bytes(pBlob);
+        pData = sqlite3_malloc( nData+1 );
+        if( pData==0 ) fatalError("cannot allocate %d bytes", nData+1);
+        rc = sqlite3_blob_read(pBlob, pData, nData, 0);
+        if( rc!=SQLITE_OK ){
+          fatalError("could not read the blob at %d: %s", iKey,
+                     sqlite3_errmsg(db));
+        }
+        sqlite3_free(pData);
+      }
+    }else{
+      /* CASE 3: Reading from database using SQL */
+      if( pStmt==0 ){
+        rc = sqlite3_prepare_v2(db, 
+               "SELECT v FROM kv WHERE k=?1", -1, &pStmt, 0);
+        if( rc ){
+          fatalError("cannot prepare query: %s", sqlite3_errmsg(db));
+        }
+      }else{
+        sqlite3_reset(pStmt);
+      }
+      sqlite3_bind_int(pStmt, 1, iKey);
+      rc = sqlite3_step(pStmt);
+      if( rc==SQLITE_ROW ){
+        nData = sqlite3_column_bytes(pStmt, 0);
+        pData = (unsigned char*)sqlite3_column_blob(pStmt, 0);
+      }else{
+        nData = 0;
+      }
+    }
+    if( eOrder==ORDER_ASC ){
+      iKey++;
+      if( iKey>iMax ) iKey = 1;
+    }else if( eOrder==ORDER_DESC ){
+      iKey--;
+      if( iKey<=0 ) iKey = iMax;
+    }else{
+      iKey = (randInt()%iMax)+1;
+    }
+    nTotal += nData;
+    if( nData==0 ){ nCount++; nExtra++; }
+  }
+  if( pStmt ) sqlite3_finalize(pStmt);
+  if( pBlob ) sqlite3_blob_close(pBlob);
+  if( db ) sqlite3_close(db);
+  tmElapsed = timeOfDay() - tmStart;
+  if( nExtra ){
+    printf("%d cycles due to %d misses\n", nCount, nExtra);
+  }
+  if( eType==PATH_DB ){
+    printf("SQLite version: %s\n", sqlite3_libversion());
+  }
+  printf("--count %d --max-id %d", nCount-nExtra, iMax);
+  if( eType==PATH_DB ){
+    printf(" --cache-size %d", iCache);
+  }
+  switch( eOrder ){
+    case ORDER_RANDOM:  printf(" --random\n");  break;
+    case ORDER_DESC:    printf(" --desc\n");    break;
+    default:            printf(" --asc\n");     break;
+  }
+  if( iPagesize ) printf("Database page size: %d\n", iPagesize);
+  printf("Total elapsed time: %.3f\n", tmElapsed/1000.0);
+  printf("Microseconds per BLOB read: %.3f\n", tmElapsed*1000.0/nCount);
+  printf("Content read rate: %.1f MB/s\n", nTotal/(1000.0*tmElapsed));
+  return 0;
+}
+
+
+int main(int argc, char **argv){
+  if( argc<3 ) showHelp();
+  if( strcmp(argv[1],"init")==0 ){
+    return initMain(argc, argv);
+  }
+  if( strcmp(argv[1],"export")==0 ){
+    return exportMain(argc, argv);
+  }
+  if( strcmp(argv[1],"run")==0 ){
+    return runMain(argc, argv);
+  }
+  showHelp();
+  return 0;
+}