Index: src/analyze.c
==================================================================
--- src/analyze.c
+++ src/analyze.c
@@ -1448,11 +1448,13 @@
     pIndex->noSkipScan = 0;
     while( z[0] ){
       if( sqlite3_strglob("unordered*", z)==0 ){
         pIndex->bUnordered = 1;
       }else if( sqlite3_strglob("sz=[0-9]*", z)==0 ){
-        pIndex->szIdxRow = sqlite3LogEst(sqlite3Atoi(z+3));
+        int sz = sqlite3Atoi(z+3);
+        if( sz<2 ) sz = 2;
+        pIndex->szIdxRow = sqlite3LogEst(sz);
       }else if( sqlite3_strglob("noskipscan*", z)==0 ){
         pIndex->noSkipScan = 1;
       }
 #ifdef SQLITE_ENABLE_COSTMULT
       else if( sqlite3_strglob("costmult=[0-9]*",z)==0 ){

Index: src/where.c
==================================================================
--- src/where.c
+++ src/where.c
@@ -2668,10 +2668,11 @@
 
     /* Set rCostIdx to the cost of visiting selected rows in index. Add
     ** it to pNew->rRun, which is currently set to the cost of the index
     ** seek only. Then, if this is a non-covering index, add the cost of
     ** visiting the rows in the main table.  */
+    assert( pSrc->pTab->szTabRow>0 );
     rCostIdx = pNew->nOut + 1 + (15*pProbe->szIdxRow)/pSrc->pTab->szTabRow;
     pNew->rRun = sqlite3LogEstAdd(rLogSize, rCostIdx);
     if( (pNew->wsFlags & (WHERE_IDX_ONLY|WHERE_IPK))==0 ){
       pNew->rRun = sqlite3LogEstAdd(pNew->rRun, pNew->nOut + 16);
     }

Index: test/analyzeC.test
==================================================================
--- test/analyzeC.test
+++ test/analyzeC.test
@@ -129,10 +129,24 @@
 } {6}
 do_execsql_test 4.3 {
   EXPLAIN QUERY PLAN
   SELECT count(a) FROM t1;
 } {/.*INDEX t1ca.*/}
+
+# 2019-08-15.
+# Ticket https://www.sqlite.org/src/tktview/e4598ecbdd18bd82945f602901
+# The sz=N parameter in the sqlite_stat1 table needs to have a value of
+# 2 or more to avoid a division by zero in the query planner.
+#
+do_execsql_test 4.4 {
+  DROP TABLE IF EXISTS t44;
+  CREATE TABLE t44(a PRIMARY KEY);
+  INSERT INTO sqlite_stat1 VALUES('t44',null,'sz=0');
+  ANALYZE sqlite_master;
+  SELECT 0 FROM t44 WHERE a IN(1,2,3);
+} {}
+
 
 
 # The sz=NNN parameter works even if there is other extraneous text
 # in the sqlite_stat1.stat column.
 #