diff --git a/jOOQ/src/main/java/org/jooq/InsertOnConflictWhereIndexPredicateStep.java b/jOOQ/src/main/java/org/jooq/InsertOnConflictWhereIndexPredicateStep.java
new file mode 100644
index 0000000000..1c281b36bd
--- /dev/null
+++ b/jOOQ/src/main/java/org/jooq/InsertOnConflictWhereIndexPredicateStep.java
@@ -0,0 +1,181 @@
+/*
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ * Other licenses:
+ * -----------------------------------------------------------------------------
+ * Commercial licenses for this work are available. These replace the above
+ * ASL 2.0 and offer limited warranties, support, maintenance, and commercial
+ * database integrations.
+ *
+ * For more information, please visit: http://www.jooq.org/licenses
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ */
+package org.jooq;
+
+// ...
+import static org.jooq.SQLDialect.POSTGRES;
+import static org.jooq.SQLDialect.SQLITE;
+
+import java.util.Collection;
+
+import org.jooq.impl.DSL;
+
+/**
+ * This type is used for the {@link Insert}'s DSL API.
+ * <p>
+ * Example: <code><pre>
+ * DSLContext create = DSL.using(configuration);
+ *
+ * create.insertInto(table, field1, field2)
+ *       .values(value1, value2)
+ *       .values(value3, value4)
+ *       .onConflict(field1)
+ *       .doUpdate()
+ *       .set(field2, value2)
+ *       .where(field3.eq(value5))
+ *       .execute();
+ * </pre></code>
+ * <p>
+ * <h3>Referencing <code>XYZ*Step</code> types directly from client code</h3>
+ * <p>
+ * It is usually not recommended to reference any <code>XYZ*Step</code> types
+ * directly from client code, or assign them to local variables. When writing
+ * dynamic SQL, creating a statement's components dynamically, and passing them
+ * to the DSL API statically is usually a better choice. See the manual's
+ * section about dynamic SQL for details: <a href=
+ * "https://www.jooq.org/doc/latest/manual/sql-building/dynamic-sql">https://www.jooq.org/doc/latest/manual/sql-building/dynamic-sql</a>.
+ * <p>
+ * Drawbacks of referencing the <code>XYZ*Step</code> types directly:
+ * <ul>
+ * <li>They're operating on mutable implementations (as of jOOQ 3.x)</li>
+ * <li>They're less composable and not easy to get right when dynamic SQL gets
+ * complex</li>
+ * <li>They're less readable</li>
+ * <li>They might have binary incompatible changes between minor releases</li>
+ * </ul>
+ *
+ * @author Lukas Eder
+ */
+public interface InsertOnConflictWhereIndexPredicateStep<R extends Record> extends InsertOnConflictDoUpdateStep<R> {
+
+    /**
+     * Add a <code>WHERE</code> clause to supply an index predicate to the
+     * <code>INSERT</code> statement's <code>ON CONFLICT ...</code> clause.
+     */
+    @Support({ POSTGRES, SQLITE })
+    InsertOnConflictDoUpdateStep<R> where(Condition condition);
+
+    /**
+     * Add a <code>WHERE</code> clause to supply an index predicate to the
+     * <code>INSERT</code> statement's <code>ON CONFLICT ...</code> clause,
+     * connecting them with each other using {@link Operator#AND}.
+     */
+    @Support({ POSTGRES, SQLITE })
+    InsertOnConflictDoUpdateStep<R> where(Condition... conditions);
+
+    /**
+     * Add a <code>WHERE</code> clause to supply an index predicate to the
+     * <code>INSERT</code> statement's <code>ON CONFLICT ...</code> clause,
+     * connecting them with each other using {@link Operator#AND}.
+     */
+    @Support({ POSTGRES, SQLITE })
+    InsertOnConflictDoUpdateStep<R> where(Collection<? extends Condition> conditions);
+
+    /**
+     * Add a <code>WHERE</code> clause to supply an index predicate to the
+     * <code>INSERT</code> statement's <code>ON CONFLICT ...</code> clause.
+     */
+    @Support({ POSTGRES, SQLITE })
+    InsertOnConflictDoUpdateStep<R> where(Field<Boolean> field);
+
+    /**
+     * Add a <code>WHERE</code> clause to supply an index predicate to the
+     * <code>INSERT</code> statement's <code>ON CONFLICT ...</code> clause.
+     * <p>
+     * <b>NOTE</b>: When inserting plain SQL into jOOQ objects, you must
+     * guarantee syntax integrity. You may also create the possibility of
+     * malicious SQL injection. Be sure to properly use bind variables and/or
+     * escape literals when concatenated into SQL clauses!
+     *
+     * @see DSL#condition(SQL)
+     * @see SQL
+     */
+    @Support({ POSTGRES, SQLITE })
+    @PlainSQL
+    InsertOnConflictDoUpdateStep<R> where(SQL sql);
+
+    /**
+     * Add a <code>WHERE</code> clause to supply an index predicate to the
+     * <code>INSERT</code> statement's <code>ON CONFLICT ...</code> clause.
+     * <p>
+     * <b>NOTE</b>: When inserting plain SQL into jOOQ objects, you must
+     * guarantee syntax integrity. You may also create the possibility of
+     * malicious SQL injection. Be sure to properly use bind variables and/or
+     * escape literals when concatenated into SQL clauses!
+     *
+     * @see DSL#condition(String)
+     * @see SQL
+     */
+    @Support({ POSTGRES, SQLITE })
+    @PlainSQL
+    InsertOnConflictDoUpdateStep<R> where(String sql);
+
+    /**
+     * Add a <code>WHERE</code> clause to supply an index predicate to the
+     * <code>INSERT</code> statement's <code>ON CONFLICT ...</code> clause.
+     * <p>
+     * <b>NOTE</b>: When inserting plain SQL into jOOQ objects, you must
+     * guarantee syntax integrity. You may also create the possibility of
+     * malicious SQL injection. Be sure to properly use bind variables and/or
+     * escape literals when concatenated into SQL clauses!
+     *
+     * @see DSL#condition(String, Object...)
+     * @see DSL#sql(String, Object...)
+     * @see SQL
+     */
+    @Support({ POSTGRES, SQLITE })
+    @PlainSQL
+    InsertOnConflictDoUpdateStep<R> where(String sql, Object... bindings);
+
+    /**
+     * Add a <code>WHERE</code> clause to supply an index predicate to the
+     * <code>INSERT</code> statement's <code>ON CONFLICT ...</code> clause.
+     * <p>
+     * <b>NOTE</b>: When inserting plain SQL into jOOQ objects, you must
+     * guarantee syntax integrity. You may also create the possibility of
+     * malicious SQL injection. Be sure to properly use bind variables and/or
+     * escape literals when concatenated into SQL clauses!
+     *
+     * @see DSL#condition(String, QueryPart...)
+     * @see DSL#sql(String, QueryPart...)
+     * @see SQL
+     */
+    @Support({ POSTGRES, SQLITE })
+    @PlainSQL
+    InsertOnConflictDoUpdateStep<R> where(String sql, QueryPart... parts);
+}
diff --git a/jOOQ/src/main/java/org/jooq/impl/InsertQueryImpl.java b/jOOQ/src/main/java/org/jooq/impl/InsertQueryImpl.java
index f3a3886082..7a0b6c3560 100644
--- a/jOOQ/src/main/java/org/jooq/impl/InsertQueryImpl.java
+++ b/jOOQ/src/main/java/org/jooq/impl/InsertQueryImpl.java
@@ -400,12 +400,12 @@ final class InsertQueryImpl<R extends Record> extends AbstractStoreQuery<R> impl
                     }
 
                     if (onConflictWhere.hasWhere())
-                        ctx.sql(' ')
+                        ctx.formatSeparator()
                            .visit(K_WHERE)
                            .sql(' ')
                            .visit(onConflictWhere.getWhere());
 
-                    ctx.sql(' ')
+                    ctx.formatSeparator()
                        .visit(K_DO_UPDATE)
                        .formatSeparator()
                        .visit(K_SET)
diff --git a/jOOQ/src/main/java/org/jooq/impl/ParserImpl.java b/jOOQ/src/main/java/org/jooq/impl/ParserImpl.java
index 8c1773643e..ca548dac68 100644
--- a/jOOQ/src/main/java/org/jooq/impl/ParserImpl.java
+++ b/jOOQ/src/main/java/org/jooq/impl/ParserImpl.java
@@ -446,6 +446,7 @@ import org.jooq.GroupField;
 import org.jooq.Index;
 import org.jooq.Insert;
 import org.jooq.InsertOnConflictDoUpdateStep;
+import org.jooq.InsertOnConflictWhereIndexPredicateStep;
 import org.jooq.InsertOnConflictWhereStep;
 import org.jooq.InsertOnDuplicateStep;
 import org.jooq.InsertReturningStep;
@@ -1992,8 +1993,12 @@ final class ParserImpl implements Parser {
                         doUpdate = onDuplicate.onConflictOnConstraint(parseName(ctx));
                     }
                     else if (parseIf(ctx, '(')) {
-                        doUpdate = onDuplicate.onConflict(parseFieldNames(ctx));
+                        InsertOnConflictWhereIndexPredicateStep<?> where = onDuplicate.onConflict(parseFieldNames(ctx));
                         parse(ctx, ')');
+
+                        doUpdate = parseKeywordIf(ctx, "WHERE")
+                            ? where.where(parseCondition(ctx))
+                            : where;
                     }
                     else {
                         doUpdate = onDuplicate.onConflict();